[Samsung Galaxy J7 Questions & Answers] Dro25:
SOLVED IT

I got my J700P back to Mashmallow (J700PVPU1APB7) from Nougat (J700PVPU2BQJ2). Tested it around for a whole day. So far no issues. But first some background (so you get an idea where I am coming from):

I got my phone brand new and rooted it while keeping stock rom. Went to custom rom. Softbricked it trying to go back to stock rom with root (so I could play Pokemon Go using Magisk). Succeded on my quest. Got some updates (both Marshmallow and Pokemon Go) which made it impossible to keep playing PokeGo. Softbricked it again trying to unroot. Succeded. Kept playing PokeGo. Got the damn Nougat update - which brought battery issues, network issues (calls/text), hated the settings menu, etc-. Tried to flash Marshmallow ROM through Odin. Failed. Softbrick it again through several attempts rooting, unrooting, reflashing and using Marshmallow TWRP backups. Fixed it by reflashing Nougat stock rom. Modify Marshmallow stock Rom. Flash. Succeded. :cool:​

If there is a lesson, it is that J7 softbricks for any sh*t. But so far, there is always a way out.​

So... below are instructions that worked (starting from stock Nougat). Read fully to familiarise yourself. Think if it is worth it to follow the steps (of a possible lucky idiot) and adapt them for your phone at your own risk.

---------------------------------------------------- WHAT YOU NEED -------------------------------------------------------------------

Windows PC (Odin is meant to use on windows)

Marshmallow (6.x.x) stock rom (find at sammobile.com)

Nougat (7.x.x) stock rom (as a precation/ from sammobile.com)

7zip software (7-zip.org/download.html)

Samsung USB Drivers (developer.samsung.com/galaxy/others/android-usb-driver-for-windows)

Odin Flashing Tool

Unlock OEM (android.gadgethacks.com/news/psa-enable-hidden-setting-before-modding-anything-android-0167840/)

Allow USB debugging on your phone (recovery-android.com/enable-usb-debugging-on-android.html)

Fully charged battery

------------------------------------------------------- PREPARATION --------------------------------------------------------------------

Download 7zip and install.

Find your Model Number &

current

Software Version at "SETTINGS" --->"ABOUT DEVICE"

At the SamMobile website create a free account

Go to sammobile.com/firmwares/ while logged in and download your current Software version by searching Model number. KEEP IN MIND YOUR CSC (Country/Carrier). Nougat software is 7.x.x.

Download your target software. KEEP IN MIND YOUR CSC. Marshmallow software is 6.x.x.

Unzip both downloads to obtain a file ending on .tar.md5 for each software.

Download Samsung USB drivers and install

Download ODIN and unzip.

Backup ALL your data. We WILL factory reset the device.

If you'd never used ODIN, here is a how-to: progeeksblog.com/how-to-use-odin/

how-to Recovery and Download mode: fonepaw.com/solution/enter-samsung-recovery-download-mode.html​

------------------------------------------------------------- STEPS ------------------------------------------------------------------------

Use 7zip to decompress Marshmallow ...tar.md5 file. You will get a folder with several files.

Delete the aboot.mbn file

Select the remaining files, right-click, under 7-Zip, click on "Add to archive..."

On "Archieve format:" select "tar". Click OK

Go to ODIN folder, open Odin.exe

Set your device on Download Mode and plug in to your computer

Once recognised by Odin, click on AP, and select your modified ROM

Under the Options tab, uncheck Auto Reboot

Click "Start"

Once greenlit, pull of battery and exit Odin.

Go to Recovery Mode (might take some time)

Perform "Wipe data/factory reset"

Perform "Wipe cache partition"

Power off

Repeat steps 5-14 two more times.

Turn on phone.

Done! :good:

--------------------------------------------------- SOME WARNINGS ------------------------------------------------------------------

I had my phone SIM Unlocked by idoneapps. This process re-locked SIM. Idoneapps was able to re-unlock it.

If you debloated your device... You will get all that sh*t back. :eek:

The problem seems to be precisely the updated bootloader (now J700PVPU2BQJ2 in my case). This process will not downgrade to your previous bootloader, so from now on, you either upgrade back to Nougat software, or modify every stock room to accomodate the limitation.

Sprint's Hands Free Activation is back; driving me nuts every time I restart my phone. I Force Stop application and doesn't bother me as long as phone doesn't go off.

If phone softbricks, just reflash Nougat software, wipe data/factory reset and wipe cache partition, and you recover your phone.

You will lose root. But the CF-Auto-Root-j7ltechn-j7ltezm-smj7008.tar.md5 method still works after downgrading.

For anyone interested... the only reason I figure this was because each time I tried to flash Marsmalllow stock rom, Odin failed at aboot.mbn. So i deleted it and risk it all. Wabalubadubdub!!!

Let me know who risks it and whether I luckily stumble upon the answer... or I am an idiot. Or both?

-Dro