[Samsung Galaxy S7 Edge Guides, News, & Discussion] shah22:
AN ESSENTIAL GUIDE FOR G935F/FD​

DISCLAIMER
☆THIS WILL BE A HUGE WORD WALL, SO DON'T BOTHER WITH THIS IN ADVANCE IF YOU MIND READING LARGE AMOUNTS OF WORDS ON SCREEN :D

☆THIS ISN'T A ROOT GUIDE EXACTLY BUT WHEN YOU READ THIS TILL THE END, ROOTING WILL BE AS EASY AS BREATHING FOR YOU (LITERALLY) :)

NOTE : THIS GUIDE DOESN'T APPLIES TO YOU IF YOU ALREADY KNOW BASICS AND/OR ARE ADVANCED USER WHO KNOWS GUTS OF ANDROID. THIS IS EXPLICITLY FOR NOOBS LIKE MYSELF WHO ACCIDENTALLY MESS THEIR DEVICES AND GET A BRICK !

WARNING : THIS DOESN'T APPLIES FOR ANY OTHER MODEL THEN G935F/FD, AND IS JUST FOR INFORMATIONAL PURPOSES, I WILL NOT BE RESPONSIBLE FOR ANY DAMAGE CAUSED TO YOUR DEVICE FOLLOWING THIS GUIDE.

P.S
HERE I PRESENT MY FIRST GUIDE FOR S7 SERIES, YOU CAN SAY ITS A BASIC ROOTING GUIDE AND SUCH GUIDES ARE EVERYWHERE HERE ON S7 FORUMS BUT THIS ONE CONTAINS VITAL INFORMATION WHICH I COLLECTED FROM VARIOUS SOURCES AND TRIED KEEPING IT AT ONE PLACE AND FOR THE NOOBS LIKE ME WHO DON'T KNOW WHERE TO SEARCH FOR THESE THINGS :)

ALSO AS I RECEIVE HUNDREDS OF PM'S FOR HELP REGARDING PEOPLE ACCIDENTALLY TURNING OEM UNLOCK OFF AND MESSING THEIR DEVICES, I HAD TO MAKE A GUIDE NOW SO EVERYONE CAN BENEFIT FROM THIS ;)

AND YEAH I CANNOT HELP ANYONE REMOTELY NOW, SORRY LIFE SUCKS IN AT TIMES :(

AND YOU GUYS KNOW THAT S7 SERIES ARE ALMOST EOL BY SAMSUNG SO I TRIED MAKING AN EOL GUIDE TOO :)

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INTRODUCTION

EFS :

EFS (encrypting file system) is the partition which stores nv data of your phone, that is a read only partiton and it contains nv data (non-volatile data) memory which stores all the vital data from the manufacturer which is non volatile or in other words.. not to be removed/modified in any way.. and So, this nv data kinda makes your phone a 'phone'

UFS :

The UFS is universal flash storage chip also known as nand memory in older terms, your internal memory chip on the s7 edge series.. it contains all the android partitions of your phone i.e everything your smartphone has to be a 'smartphone' ..

DM-VERITY :

Device-Mapper verification is a new security measure in latest samsung devices, it basically checks system integrity i.e to check if system partition is modified by any method .. if your system partition is modified even willingly by yourself by any method like non-systemless root/mod/custom binaries etc, dm-verity will kick in and prevent your phone from booting normally. DM-verity is explicitly present in recovery partition which prevents boot on activating and it kicks in through a check inside the stock kernel which activates it.. apparently, removing dm-verity in recovery or kernel makes the device boot-able again.

DRK :

DRK or device root key is present in efs partition of your phone, DRK is a device-unique asymmetric key pair that is signed by Samsung's root key through an X.509 certificate, this certificate proves that the DRK was produced by Samsung. DRK is explicitly present in EFS partition. If due to any reason your drk gets corrupted/deleted, you get a permanent type of dm-verity error and your phone will not boot even stock samsung roms without dm verity disabler zips ..

NV DATA :

Non-volatile data is present on efs partition and includes, device specific vital manufacturer binaries which are never to be modified/removed in anyway. This includes device specific network certificates, IMEIs, SERIAL numbers, bluetooth ids/mac addresses, DRK, nfc parameters and others etc ..

PARTITIONS :

Android adopts linux like partitions and file tables, but most of the partitions present on samsung phones are not to be modified/messed up in any way, other then backing them up. The most common partitions to modify/format include :

1. DATA

2. CACHE

3. DALVIK CACHE

4. SYSTEM

But system partition is often recommended to not modify/format for the reasons I will explain further down in the guide ..

A partitions screenshot of s7 edge G935F running a stock rooted rom on version 8 binary

The highlighted ones in yellow contain your nv data..

NOTE : ITS A VITAL STEP TO BACKUP ALL NV DATA PARTITIONS AFTER ROOTING (SHOULD BE THE FIRST THING TO DO AFTER ROOTING! )

PARTITION STYLE/IMAGE TYPE :

S7 series (exynos) partition table is A type on oreo stock firmware and until pie based custom roms.. one ui 2.0 introduced A/B style partitioning. Only difference between them is about how hard magisk implementation is in A/B and also the absence of ramdisk. You can get more info in magisk's documentation on github.

FIRMWARE TYPES :

All firmwares before the 10th binary update are called as A firmwares, the 10th or 0 one being called as A and after onwards from that we call the binaries as B firmwares i.e all firmwares from G935FXX1XXXXX to G935FXX9XXXXX will be called A firmwares simply, the 10th one being G935FXXAXXXXX and after that B firmware starts as G935FXXBXXXXX and then binaries continue like C/D/E/F if samsung wanted to update the device further.. S7 exynos are currently on 8th version binary.. where the binary number is actually the bootloader number and you cannot downgrade to lower version binaries from a higher version ..

Also the B firmwares are a very special case, will explain later further down later.

BOOTLOADER VERSION :

Refer to the above paragraph. Numbers/alphabets after XX and before XXXXX denote the version number of the binaries or in other words the bootloader version, which after upgrading to a higher version cannot be downgraded to a lower bootloader version ..

WHAT IS AP/CP/CSC/BL/PIT?

AP is Application Processor, known as PDA in older terms, the core android of the flashing package, CP being the Core Processor also known as modem, while CSC is Consumer Software Customization which contains regional/country based settings for your phone which includes network settings and custom preloaded software, also to mention that CSC has two types CSC and HOME_CSC ..

CSC contains the pit file which partitions and formats the phone before flashing in odin, while HOME_CSC doesn't include pit file and is meant to upgrade/dirty flash without wiping data in odin.. PIT means partition information table, if you are flashing CSC you don't need to manually extract and place pit file in odin as this is automatically done when flashed using CSC..

ODIN :

Odin, the lord of the dead as known in norse mythology is actually a lord of dead samsung phones too :) you already know what this is, but in case if you really don't; then this is a flashing software for samsung phones and you don't need to select any advanced options in odin when flashing.. just select auto-reboot and f.reset when flashing stock firmwares - all other options are obsolete and/or have no use for s7 series devices. Also when flashing any recovery don't tick auto reboot just f.reset and manually force reboot from download mode to custom recovery using key combinations :)

DOWNLOAD, RECOVERY MODE, SAFE MODE AND FORCE REBOOT :

While phone is turned off, holding vol down+home+power buttons will make you go in download mode.

And while phone is off, holding vol up+home+power buttons will make you go in recovery mode ..

Holding vol down after samsung animation comes during boot would make you enter in safe mode (this option is obsolete since in most bootloops we cannot go in safe mode because phone isn't booting properly to accept safe mode key input)

Hold vol down+home+power buttons on any screen to force reboot phone ..

DOWNLOAD MODE INFO :

There are details written in download mode which are very useful for diagnosing various issues.

Such as :

>Real Model Number : displays real phone's hardware model.

>System Status : displays intact-ness of /system partition.

>Binary Status : displays intact-ness of other partitions like boot (kernel) or recovery etc.

>KNOX Status : displays the hardware e-fuse status for warranty purposes. Anything other then 0x00 means its tripped.

>Letters B/K/S : letter B means bootloader version number, K for kernel's and S for system's version number. You cannot flash any firmware with lower numbers then displayed here because secure bootloader will always block it.

UPLOAD MODE :

There is not much info on this or any info at all for the matter. All I know per my personal experience is that it happened due to SBL (secure bootloader) error after flashing an incompatible firmware. It can be due to any other software or hardware reasons, but my guess is that it protects phone from becoming a complete brick in case of bootloader error or corruption. But again, its so scarce that hardly any reliable information exists about it and I'm not gonna brick my phone just to see if it really 'works' 😃

FRP LOCK :

FRP lock is the factory reset protection, it kicks in two ways.

1. You had oem unlock off and you forgot to delete your/last google account on device before factory resetting it and for some reason you also forgot that google account's password, so this frp lock kicks in and you need to login with that last google account to regain access to your phone, this is basically an anti-theft measure, also ironically there were/are ways to bypass it too ..

2. If you disable oem unlock after rooting/modifying/installing custom binaries or you try to root/modify/install custom binaries without enabling oem unlock first, you get custom binary blocked by frp on next boot, for solving this you just need to flash back stock rom.. and login with last google account password if required .. :)

3. Its a bit same like no. 2, but this one is a dreaded and notorious issue.. happens when your drk or efs gets corrupted due to any reason and you also "Accidentally" turn OEM Unlock OFF (lmao) . Now when you flash custom binary you get the same frp lock as no. 2, BUT you cannot boot stock rom back to Enable OEM Unlock due to drk error/efs corruption (which prevents even stock rom from booting up because of dm-verity error) and you cannot fix drk/dm-verity error by flashing no verity zips.. because custom binary block by frp error.......

So now you know its not a good idea to do "Accidents" :D

COMBINATION BINARIES :

Combination binaries are troubleshooting firmwares developed specially for repairing by samsung which don't have dm-verity checks as well as no developer options either, which mainly can be used to fix imei/efs issues AFTER restoring a backup which you are SURE to be WORKING and taken from an earlier/working environment..

Sometimes combination roms can fix efs/imei and network issues without restoring a working earlier backup (in case of some software bug), though this only works if the original factory efs of your phone is intact ..

NOTE : AS OF NOW, LATEST COMBINATION ROMS FOR VERSION 7 AND 8 BINARIES AREN'T AVAILABLE ON THE POPULAR AND TRUSTWORTHY SOURCES - NOT EVEN ON PAID ONES. SO EITHER DON'T UPGRADE YOUR PHONES TO LATEST BINARIES OR DON'T MESS THEM UP SO THEY DON'T REQUIRE COMBINATION ROMS TO FIX THEM :)

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MAIN GUIDE AND ISSUES TROUBLESHOOTING

NOW THAT YOU HAVE READ MY ENCYCLOPEDIA, I WILL BEGIN WITH MY DARWIN PHILOSOPHIES 😃

1. DEVELOPER OPTIONS AND OEM UNLOCK :

Developer options are the first step when you want or even think of modifying/rooting your device in anyway. You go in about section of your phone and tap build number 8 times to enable developer options and then you need to ENABLE OEM UNLOCK BEFORE MODIFYING/ROOTING YOUR DEVICE IN ANYWAY POSSIBLE

FLASHING ROMS AFTER ENABLING OEM UNLOCK DOES NOT CHANGE ITS STATE

BE WARNED : CLEARING DATA OF SETTINGS APP OR FOLLOWING ANY GUIDE ON INTERNET TO DISABLE DEVELOPER OPTIONS AFTER ROOTING/MODIFYING YOUR PHONE CAN RESULT IN OEM UNLOCK BEING TURNED OFF AND YOU GETTING THE CUSTOM BINARY BLOCKED BY FRP MESSAGE

AND YES PLEASE DON'T ACCIDENTALLY TURN OEM UNLOCK OFF FOR HEAVEN'S SAKE

2. USB DEBUGGING :

Although not vital, but usb debugging is needed for using adb from your pc and adb has many useful commands if you like digging in the linux shell, plus many no-root apps require adb commands to make them run some useful functions without root.. I recommend keeping it on just in case.

3. DM-VERITY ERRORS :

Ah yes, I hate this one, this is one of the most notorious errors I have ever seen, DM verity as told above is a system integrity check for modifications, but this dm-verity thing on occasion can make a hard brick coupled with some kind of encryption in the kernel/bootloader, Master @Chainfire describes such behaviour in one of his posts here, it was on nougat though and I can only expect it to be worse on oreo ..

https://xdaforums.com/showpost.php?p=72204306&postcount=978

In simple terms a s7 can become a partial hard brick IF user had no access to a working rom (due to dm-verity) and custom recovery is broken/can't be flashed (due to OEM Unlock being turned off) ..

So, if anyone modifies their system partition after root without disabling dm-verity check in the stock kernel or they root using non-systemless method or they did a swipe for system modifications in twrp or they installed any non-systemless mod, they get dm-verity error.. For most part a dm-verity error due to a modified system partition on a rooted phone can be easily fixed by flashing no-verity zips in twrp recovery ..

OR by flashing a stock firmware of matching binary through odin ..

Even if you have accidentally turned oem unlock off, you simply reflash stock firmware and go in developer options to re-enable oem unlock. This is what I call type 1 dm-verity which is the easy one to fix ..

NOW, lets see another scenario where some people accidentally turned oem unlock off (yeah believe me there are tons of users doing this these days lol) and for those people dm-verity was not going away even after a stock firmware reflash and because they turned OEM UNLOCK OFF they could NOT flash custom binaries to bypass dm-verity either.. HENCE THEIR DEVICE WAS IN A STATE OF SEMI-PERMANENT HARD-BRICK..

My search revealed that a corrupted/missing DRK in EFS partition was actually the root cause of this type of dm-verity error, such unfortunate users CANNOT EVER REVERT BACK TO A STOCK UNMODIFIED ROM (without restoring an intact DRK backup) and they ALWAYS HAVE TO FLASH NO VERITY ZIPS TO USE/BOOT STOCK ROM..

But if OEM UNLOCK IS TURNED OFF, they get STUCK BADLY because device rejects any custom binaries like no-verity zips and twrp etc ..

My further search concluded that since the stock recovery kicked in dm verity, So if the AP file of firmware is extracted and stock recovery is deleted from it, while the boot.img is renamed as recovery.img and only system.img alongwith renamed recovery.img is repacked and flashed alongwith BL, CP and CSC, it allows users to BOOT into stock rom to ENABLE OEM UNLOCK AGAIN and use their device with custom binaries, and so their device is back to the living once more :)

The exact steps are as follow :

1. Extract the correct matching-binary firmware package.. then extract the AP file, and copy boot.img and system.img to a new separate folder ..

2. Rename boot.img to recovery.img and repack this renamed recovery.img alongwith system.img (only these 2) using autotar tool (I've posted the link to autotar tool now although it gets detected as a virus, So download at your own risk) or any other tar packing utility ..

AutoTar Tool

3. Flash this modified AP using latest odin along with BL, CP and CSC (not HOME_CSC) and only tick auto reboot and f.reset in odin options ..

Your phone should boot now and you can ENABLE OEM UNLOCK to flash custom binaries and make your phone usable again.. personally tested that this method works ..

BE WARNED THAT THIS METHOD REQUIRES ATLEAST 10% BATTERY FOR FLASHING AND BOOTING

Since many devices had been hard bricked for months and battery being drained completely, they couldn't boot or complete flash due to their phone becoming dead in the middle of flashing process or booting process ..

I recommend charging phone by a wireless charger in this state (since wireless charger is said to be working even in bricked state, also connecting it to a charger while in download mode may give it some charge) or simply try continously to boot it, if flash using above method is successful then don't reflash anymore just try to boot phone while putting it on charger ..

And hopefully your device will get out of this dreaded dm-verity + frp lock due to custom binary ..

Here's my original post for such dm-verity fix : https://xdaforums.com/showpost.php?p=82294339&postcount=11

WARNING : MULTIPLE INTERRUPTED/INCOMPLETE FLASHES DUE TO NO BATTERY OR BATTERY DYING IN THE MIDDLE OF FLASHING PROCESS CAN CAUSE PERMANENT UFS CHIP HARDWARE DAMAGE !!

END NOTE : ALL OF DM-VERITY ISSUES ONLY HAPPEN ON A FULLY STOCK ROM WITH STOCK BOOT/KERNEL AND STOCK RECOVERY, ONCE A CUSTOM ROM OR CUSTOM BOOT/KERNEL AND CUSTOM RECOVERY ARE FLASHED, THEN THERE MAY NOT BE A NEED TO FLASH NO VERITY ZIPS, BECAUSE DM-VERITY MAY ALREADY BE DISABLED IN THE CODE. REFER TO YOUR RESPECTIVE ROM THREAD FOR THE REQUIRED INFO.

4. FORCED ENCRYPTION :

My personal experience and testing with root on android 8.0 stock oreo made me conclude that for some reason, the latest twrp as well as tkkg's modified twrp (which only supports quota) fails to mount /data even after formatting, when we reboot first time into system after formatting data and then go again in twrp, twrp fails to see /data again ..

Well, this is not a huge problem BUT if due to any reason your phone got in a non-fixable bootloop and you still got valuable data on it, then there's no practical way to recover it, except copying and moving it from twrp to external sd card/usb otg ..

So yeah an accessible /data is a big factor for me to have it working ..

Tkkg's post on encryption : https://xdaforums.com/showpost.php?p=77296095&postcount=2228

link where he says he hasn't added encryption support : https://xdaforums.com/showpost.php?p=77314388&postcount=1251

I first thought that latest official/tkkg's twrp would have fixed this problem, but even when forced encryption is disabled using zips, every twrp I tried could not see /data partition ..

EDIT : OFFICIAL TWRP 3.3.1+ WORKS BUT WE NEED TO FLASH MAGISK RIGHT AFTER BOOTING TWRP FOR FIRST TIME AFTER DOING A FORMAT DATA UNDER WIPE OPTIONS, AFTER THIS REBOOT TO SYSTEM, AND ENCRYPTION WON'T COME BACK AND YOU WOULD BE ABLE TO ACCESS DATA AFTER EVERY REBOOT IN TWRP !!! SEEMS LIKE IF NO MAGISK = NO /DATA ACCESS IN TWRP OR IN OTHER WORDS "FORCED ENCRYPTION"

5. ODIN ISSUES :

Many users on the forums reported issues with flashing via odin, my own experience and research tells me it can be due to :

》You're using a wrong model firmware.

》You're using a counterfeit/modified phone whose real hardware model is different then what's displayed.

》Your phone's internal nand storage hardware got faulty and fails to write anything on it.

》Odin's version is wrong and/or you got a fake software (can happen when downloading odin from fishy webs)

》Either your PC/Samsung usb drivers/usb cables/usb ports got some bugs/issues.

》Smart switch is running in background processes and it is known to mess with odin flashing (often that's the culprit)

You can try to download odin from a reputable web, re-verify that you're using correct firmware and smart switch isn't running as a background process. Also try checking with some other usb cables/ports or PC. Also verify that your phone isn't a counterfeit product (hardware modified)

If you were already rooted or flashed a custom rom before, and you're sure that OEM Unlock is enabled in developer options, you can try flashing twrp in odin and then a custom rom through twrp - as a last resort. But if you haven't rooted/enabled OEM Unlock before, this won't work either and you may had to take your phone to a repair shop :(

Heads Up : Incase you didn't knew, but if odin fails a flash or flash gets interrupted at or during sboot.bin (the bootloader flashing step) or you flash a wrong bootloader which unfortunately download mode couldn't stop from getting flashed, it can cause hard bricking due to corrupted bootloader (no download mode) and can only be fixed via UART interface using a hardware repair box. Ofcourse this doesn't include failed flashes at sboot which are due to download mode blocking the flash (its actually protecting itself from flashing a wrong/incompatible bootloader)

6. ROOTS AND SYSTEM-LESS ROOTS :

I guess in all my rant you must have noticed that the biggest problem comes in when efs partition becomes corrupted specifically, now when i searched countless pages of users and their issues I came to conclusion that somehow ROOTS using system modifications and also TWRP with system modifications enabled HAVE A HIGHER CHANCE TO MESS/CORRUPT EFS PARTITION, specifically the FULLY MODIFIED CUSTOM ROMS OUT THERE (AND NO I AM NOT BLAMING ANY CUSTOM ROM OR DEV, JUST THAT A FULLY ACCESSIBLE SYSTEM PARTITION HAVE MORE RISK OF CORRUPTING EFS PAR MY OBSERVATION- I hope to be wrong lol)

Now, thats where system-less roots come in !!

THEY ARE SIMPLY AWESOME AND NOT BECAUSE I AM A FANBOY OF MAGISK BUT BECAUSE THEIR ACCESS TO SYSTEM PARTITION IS TOTALLY INDIRECT WHICH INTURN PASSES SAFETY NET CHECKS TOO.

SYSTEM-LESS ROOTS ARE ONE OF THE BEST EVOLUTION OF ROOTS, IN MY VIEW SYSTEM-LESS ROOT AND SYSTEM-LESS CUSTOM ROM DEV BASE ARE ONE OF THE BEST ROOT AND ROM RESPECTIVELY NOT BECAUSE IT ONLY PERFORMS WELL AND FEELS STABLE BUT BECAUSE IT HAS THE LEAST TENDENCY TO CORRUPT EFS BECAUSE IT IS MUCH MORE CLOSER TO STOCK ROM! A BIG SHOUT OUT TO @_alexndr FOR HIS SUPERB SYSTEM-LESS DEV BASE.. AND THE BEST THING IS THAT DOWNLOAD MODE REPORTS SYSTEM AS OFFICIAL AND PASSES SAFETY NET EVEN WHEN YOU'RE ROOTED AND USING EDXPOSED !

THAT BEING SAID, THE BIGGEST REASONS OF EFS CORRUPTIONS ARE NOT DUE TO CUSTOM ROMS, BUT DUE TO THE VARIOUS MODS AND INCORRECT FOLLOWING OF FLASHING/INSTRUCTIONS WHICH CAUSE THIS.. AND SOMETIMES FAULT/ERROR OF THE HARDWARE TOO.. AND VERY RARELY ITS A MISTAKE ON DEV'S PART ..

Moving on to root types, you got Super SU along with its system-less root option and Magisk (has system-less root as default); both have hiding root options as well, you just need to choose your preference and flash it in twrp.. I really don't recommend king root or any other root types !!

FOR USING SYSTEM-LESS ROOT KEEP SYSTEM READ ONLY IN TWRP!!! (DO NOT SWIPE TO ALLOW SYSTEM MODIFICATIONS WHEN BOOTING IN TWRP FOR FIRST TIME AND TICK DON'T ASK ME AGAIN)

BE AWARE ! CHOOSING SYSTEM MODIFICATIONS IN TWRP WILL AUTOMATICALLY CAUSE NON-SYSTEMLESS ROOT METHOD !

ALSO : WITH MAGISK ONE NEEDS TO FLASH IT AFTER FLASHING NO VERITY ZIPS IN TWRP (IF USING MAGISK IN NON-SYSTEMLESS MODE OR DUE TO DRK BEING CORRUPTED)

Please note that CF Auto root is now obsolete for s7 series on version 5+ binaries ..

7. BOOTLOADER EXCEPTION BUG (SBL ERRROR) :

Another rare and possibly dangerous bug, ironically I encountered it on my first days of getting this device :)

That screen was terrifying for a noob like me at that time lol, now how did I got it in first place ?

Yeah I tried to be a smart-ass and flashed a normal bootloader along with a combination firmware in odin lol (tried to bypass bootloader blocking flash of lower binary version), flash was successful and when phone booted it caused bootloader exception bug ..

And what I did to solve it ? Simply hold home button until you see upload mode and then force reboot by combination keys and then immediately hold download mode combination keys to go in download mode and reflash stock rom :)

Seems like other people on forums weren't that lucky to get out of this error easily :(

Possibly, this error can also be caused by some hardware fault/bug.

Further investigation revealed that SBL error (secure bootloader error) is particularly a semi-corrupted bootloader which in reality would cause the device to become a hard brick which can only be recovered through UART interface using a hardware box (which essentially requires us to open phone's guts), but instead it caused bootloader to get in a fail-safe 'UPLOAD MODE' which is surprising actually because any wrong bootloader flash is sure to make your device a permanent brick.

So better NOT cross-flash firmwares or bootloaders not designed for your phone, specially which are apparently made for same hardware as yours but you may not be that lucky to get in upload mode after that, So :

>Don't try to flash a G935F (global) bootloader on a G935W8 (Canada variant) or G935V/T/A/U (US variants) or G9350/K/L/S (Chinese/Korean/Hongkong variants etc) and vice versa.

>Don't try to flash a G9350/K/L/S (Chinese/Korean/Hongkong variants etc) bootloader on G935V/T/A/U (US variants) or G935F (global) or G935W8 (canada variant) and vice versa.

>The above instructions includes both normal and combination firmwares. Also don't try to flash normal firmware's bootloader with combination firmware or vice versa.

>Don't try to downgrade bootloader by 'any method'..

>Don't use any 'patched odin' to flash an incompatible firmware.

>Don't try to flash bootloader using flashfire/twrp or any other mobile flashing utility.

8. NETWORK AND IMEI'S ISSUES :

Regarding loss of network signals, there are 2 possibilities, either that your imei got deleted/corrupted due to a bad efs partition or your phone's imei was changed and a network certificate patch was used to make it working, and you reflashed your phone through odin or any other flashing method which removed that network certificate patch and you lost your signals ..

Now both can be fixed only by a box or box-like alternative see this thread link for more info :

1. https://xdaforums.com/s7-edge/how-to/fix-imei-downgrading-g935f-fd-t3947911

Remember : There's always a risk of bricking your device or screwing it further by using such (box-free) tools ..

Moreover, signals can be lost when flashing old modem on newer bootloader, it can be fixed by reflashing correct firmware (matching bootloader version) for your phone ..

Signals can also be lost by a bugged out csc (probably due to a bad efs), for solving this you can try changing your csc code by flashing different csc firmware with matching bootloader version (preferably a single csc firmware like dbt/xeu) and then reflashing your original csc to revert back and applying the fix mentioned in No. 1 thread link above.

A bugged out/corrupted efs is often the main culprit for signals issue, which needs combination rom with matching bootloader version and/or an earlier working efs backup to fix it.

See this thread link below for more on this :

2. https://xdaforums.com/s7-edge/how-to/guide-how-to-fix-check-drk-imei-issues-t3379516

Another option is if you got an older working efs backup, just restore it and then give appropriate permissions and then flash combination rom for your rom, but problem is.. you need quite a bit of linux command knowledge and updating the permissions according to your own phone and android version (originally it was done on note 4) plus combination roms for latest binaries are not getting released into public now !!

Please refer to this thread link of note 4 below :

3. https://xdaforums.com/note-4/general/fix-drk-dm-verity-factory-csc-serial-t3422965

As a token I provide my phone's DRK, the prov_data folder (for getting rid of dm-verity error by following No. 3 thread link of note 4 above).. if anyone experienced and interested enough wants to experiment to fix their drk/dm-verity errors permanently ..

NOTE : As policy of xda, I'm not sharing any imei/personal phone data, but just a DRK encrypted key which could benefit users with dm-verity and drk errors, if anyone finds it against xda's terms or rules, feel free to report my shared prov_data (but it has already been shared before for note 4)

BUT EVEN WITH THIS PROV DATA AND SUCCESSFULLY GIVING PERMISSIONS YOU WOULD STILL NEED COMBINATION ROM TO FIX DRK AND SIGNALS/IMEI AS STATED IN NOTE 4 THREAD !

ALSO THIS WILL ONLY WORK ON DEVICES BEING ROOTED AND IN WORKING CONDITION !

TIP : WELL, SOMETIMES YOU TRAVEL ALL THE WORLD TO FIND SOMETHING WHEN ITS ALREADY THERE IN YOUR HOME OR NEIGHBOURHOOD :D AND SAME THINGS CAN HAPPEN WITH THESE ISSUES TOO, IN THE END YOU DID EVERYTHING YOU CAN TO TRY AND GET YOUR SIGNALS FIXED WHEN YOU JUST HAD TO REPLACE YOUR SIM CARD LOL

SO YEAH SIM CARD CAN BE FAULTY TOO, ALWAYS TRY CHANGING SIM CARDS FIRST IF YOU GET ANY NETWORK ISSUES. ALSO, SOMETIMES ITS THE PHONE'S MODEM HARDWARE THAT'S FAULTY AND YOU CAN'T DO ANYTHING ON THE SOFTWARE SIDE.

9. BATTERY DRAIN ISSUES :

Ever since the version 7 binary update i.e december 2019 security patch and later, I noticed my phone draining battery heavily due to android system and kernel.. and I lost almost 50% of s.o.t and also created this warning thread here :

https://xdaforums.com/showpost.php?p=81410317

SO YEAH. I RECOMMEND USERS TO NOT UPDATE TO VERSION 7 BINARIES OR LATER !! IT WILL ONLY CAUSE A DELIBERATE SAMSUNG CREATED BATTERY DRAIN TO PUSH USERS FOR UPGRADING THEIR PHONES !

10. BINARY UPDATES :

Since samsung has officially made s7 series eol, the updates they will now push would always to some extent, try to limit device in some ways - like the huge battery drains with version 7+ binaries and the fact that you cannot downgrade, the whole point is that they want users to upgrade their phones and hence they will push such updates which will further limit our device !

Also let me tell you, once S7 reaches Version 11 or in other words 'B' binary, its stated that twrp will not work and I think even root will be much harder to achieve and sustain.. if I'm wrong then I request someone to please correct me :)

ALL IN ALL, UPGRADING BINARIES WILL ONLY CAUSE YOU TO BE STUCK ON EVEN WORST FIRMWARES !!

I REALLY RECOMMEND TO NOT UPDATE YOUR PHONES ANYMORE !!

11. PERSONAL RECOMMENDS :

I am not the one to recommend anyone something but if you do want to get root but want stability, unmodified system-partition, less risks of your phone being messed up or simply you care for your phone's health; this is still a great phone :)

I heavily recommend alexndr's custom devbase rom or if you don't want that debloated stock rom, you can just use his system-less devbase root option too.. along with system-less Magisk ..

AND MY BIGGEST RECOMMENDATION IS :

ALWAYS BACKUP YOUR EFS AND NV DATA PARTITIONS FIRST THING AFTER ROOT !!!

This is it from this noob guide of mine, thanks for reading such a long "rant", I hope it would benefit you. My original aim was to create an END OF LIFE GUIDE for S7 series combining various info, and I think I'm partially successful in it :)

I'm always open to add new info and/or correct anything which I mentioned wrong, also if you need any help feel free to post a reply.. I'm not able to help remotely anymore though :(

But no matter, all the info I learned remains archived in this thread till the end of times ;)

USEFUL LINKS :

ODIN

ODIN

SAMSUNG STOCK ROMS

SAMSUNG USB DRIVERS

OFFICIAL TWRP

SUPER SU

SUPER SU

MAGISK

MAGISK

SYSTEM-LESS ROOT DEVBASE

SYSTEM-LESS DEVBASE ROM

NoVerityOptEncrypt

NoVerityForceEncrypt

ALL CREDITS TO THEIR RESPECTIVE CONTRIBUTORS​