[Galaxy Note II General] Sudo77:
N7100 4.3 to 4.1.2 Downgrading Guide (Comprehensive)​

Read First!:

Hi there! Welcome to my first guide to downgrading your Jelly Bean OS back to the Stock 4.1.2. By reading this guide I will assume that you have ALREADY TRIPPED YOUR KNOX FLAG (0x1), IF YOU DON'T KNOW WHAT KNOX IS, DON'T USE THIS GUIDE and you have decided to downgrade to stick with 4.1.2 for a better user experience as I did. A couple of notes before we begin, as I feel I need to inform you of the risks you are about to take, however, I WILL NOT BE RESPONSIBLE FOR YOUR DECISIONS / BROKEN DEVICES, ETC by following this guide. This doesn't mean that the guide is faulty by any means (as I did much testing) but that you are willing to take the risks and be accountable for them. Just to be crystal clear.

By upgrading to 4.3 you have already locked your bootloader, which means the device won't let you downgrade to any lower versions or custom ROMS by directly flashing them though ODIN. Till now there has been no fix for unlocking it across all devices and this guide is not able to fix it. However, it can remove the KNOX application, which prevents all root access to the device. This will allow better methods for rooting if you ever require it.

I must also inform you that your IMEI number will temporarily fall when downgrading to 4.1.2. This is common. IMEI registers your device to the mobile network, similar to your PC's MAC Address to connect you to the internet so there can be communication. IMEI and other important information is stored your efs partition which is then read by your modem. 4.3 uses a NEW efs V2 which can't be read by older modems. When you downgrade to 4.1.2, you also downgrade the modem and IMEI can't be read. TO FIX you need to simply revert to your new modem. So it is benificial to create an efs/modem backup in this guide (Just in case).

Once you downgrade to 4.1.2, the bootloader will disable system updates from Samsung. You won't need them anyway, because you will be staying with 4.1.2, if not, then why are you reading this??? But you can directly flash back to official 4.3 via PC Odin as the bootloader allows this. You can get your updates back when on 4.3.

- You must have Wifi active on you phone at all times / Access to Google Playstore

- You need at least 1.5 - 2 GB free in INTERNAL memory free

- Read carefully / take your time

Now that all is clear, lets begin!

Tools Needed:

- Samsung USB Drivers For Windows Download Here

- Register to Sammobile.com for firmwares (Your original stock 4.3 AND desired 4.1.2) Here

- PC Odin (v3.09) Download Here

- Custom Recovery philz-touch V5 (V6 is too buggy) Download Here

- Dr. Ketan's Multitool Advance V6 (Courtesy of Dr. Ketan) Download Here

- Mobile ODIN PRO @ Playstore Purchase Here

- SuperSU (Extract "superuser.apk" from "common" folder) Download Here

- EFS Tool Samsung N7100/900 Here

- (IMPORTANT! 4.3 Modem File) Modem.bin (Extract from the .zip file, I find XXEMJ5 modem works well) Here

Instructions:

Notes: When I say enter DOWNLOAD MODE, power off your device, hold VOLUME DOWN + HOME KEY + POWER KEY until your device displays a warning message. Then press VOLUME UP.

When I say enter RECOVERY MODE, power off your device, hold VOLUME UP + HOME KEY + POWER KEY until your device displays NOTE II N7100 screen then let go.

1.) Download and install Samsung USB drivers for Windows if you haven't already, for PC mobile communication.

2.) Go to sammobile.com (listed above) and get a copy of your official 4.3 firmware AND your desired 4.1.2 version that you want to downgrade to. Pay Attention to get your correct country and carrier ROM! (Smartphone > Android > Galaxy NOTE II N7100 > Your Country/Carrier).

3.) Download and extract Odin 3.09 to your PC's desktop, Right click and choose "Run as Administrator".

4.) On your phone, enter Developer Mode by going to Settings > More > About Device and tapping "Build Number" a few times, until the message "You are now a developer" appears. Back in settings, go to Deveoper Options and enable "USB Debuging".

5.) Connect your phone to PC via USB cable and enter DOWNLOAD mode.

6.) PC Odin should detect your device, by showing a blue bar (COM PORT #) and "Added!" message should pop up. Extract philz-recovery V5.md5 and flash it by checking the checkbox next to AP, then click AP to add the file, and click Start. (Make sure ONLY Auto-reboot and F. Reset time is selected in Odin). --> This is the step that trips KNOX counter.

7.) Wait for green "PASS" to show in Odin and your phone to finish reboot. Now on your PC, go to your GT-N7100 directory and move (DO NOT EXTRACT) [1] Dr. Ketan's Multitool V6.zip AND [2] superuser.apk AND [3] modem.bin (your N7100 4.3 modem) to the "Download" folder on your phone.

8.) Extract your .md5 4.1.2 firmware, and move it to this folder on your phone as well. (4 files in Download folder now)

9.) On your phone, enter RECOVERY mode (you will see a purple skinned custom recovery), touch "Install zip" and "Choose zip from sdcard"

10.) Find your Download folder, and touch Dr. Ketan's Multitool V6.zip. Touch "Yes" to confirm install.

11.) Here, agree to the Terms of Use and touch Next a couple screens. Touch Proceed with Multitool and do the following:

- Root Device/Inject Busybox (Next)

- DeKNOX Device (Next)

- Skip all the rest (Next a couple screens)

- Do NOT change the rest (Next a couple screens)

- When prompted to run, touch RUN. Next and reboot.

12.) Now that your device is KNOX free, go to My Files > All Files, and find the Download folder. Touch superuser.apk. You will get a warning message, just hit "Settings" and find "Unknown Sources" and make sure it is checked. Touch "All" and "Install".

13.) In Supersu, touch "Continue" for Su Binary Update. Select "Normal". A message may indicate it failed, but it still funtions after a little wait.

14.) Install Dr. Ketan's EFS Tool Samsung N7100/900, Just for safety, backup your efs. Grant permissions from Supersu when asked.

15.) On your PC, go to your N-7100 root folder, you will see a new folder called "MyEFS#####" with a file inside (efs.img), copy this folder to a safe place on your computer and keep it.

16.) Install Mobile Odin Pro from Playstore. Run app, grant permissions, download updates.

17.) In Mobile Odin, touch "Open file..." > "Internal SD-card" and navigate to your Download folder. Select your 4.1.2 firmware. Hit OK.

18.) Make sure "Wipe data and cache" AND "Wipe Dalvik cache" is checked (If not, you will see a lovely bootloop, a big NO-NO). Finaly, hit "Flash Firmware" > "Continue"> "Check" for safety sakes.

19.) Wait a little while (About 2 reboots), you are now reverting to 4.1.2. You will be greeted with a welcome screen (Welcome back! :D) Sign-in to your device.

20.) Back on 4.1.2, all is well... Except IMEI!!! To fix, go back into Mobile Odin app. Select "Open File..." > "Internal SD-card" > "0" > "Download" > Select "modem.bin".

21.) Touch "Flash Firmware" > "Continue". And wait for reboot. (DO NOT wipe cache this time) ~ DONE! ~ (Optionally, you can now use Triangle Away to clear flash counter, and remove Supersu and Mobile Odin for a cleaner look)

======================================================================================================

If you have any questions, comments or concerns, post here first before you attempt. Say thanks, if it worked for you. Finally, thank YOU for reading my guide. :D