The Galaxy S2 users received the official update to Android 4.1.2 Jelly Bean several months ago but, since then, they have flashed new custom ROMs. This guide teaches you how to successfully unroot it and restore to stock firmware. Read the entire post and you should be able to complete the unroot process fast and easy.
In order to make sure that you successfully apply all the changes, you will first have to read the guidelines below. Here's what you need to know:
- Use this guide only for the Samsung Galaxy S2 model number I9100. Don't try to use this tutorial with any other Android smartphone or tablet.
- Your device will be restore to its stock Android 4.1.2 Jelly Bean ROM and you will lose access to any applications that require root permissions.
- Create backups of all the data that is currently stored on your phone. This guide might remove all the files from your smartphone, which is why you have to make sure that you have copies of all your most important files.
- The warranty of your device will be restored after you finish completing the changes.
- Make sure that your computer has all the Samsung USB Drivers installed on it.
- Disable any antivirus apps from running on your computer. Such programs are usually blocking ODIN and you won't be able to complete the tutorial.
- Make sure that your Galaxy S2 battery has enough power left before the device shuts down.
- Enable USB Debugging from the Android Developer Options.
- This is a guide for advanced Android users and you shouldn't use it in case you don't know what you're doing. You can't blame us in case you lose any data or you brick the phone.
- Read the entire post first and then begin the unroot process. Don't skip any steps that I have listed below.
Since you've read all of the above, it means that you can continue to the next part of this post.
How to Unroot Samsung Galaxy S2 I9100 and restore it to Android 4.1.2 Jelly Bean firwmare:
- Download the Firmware file from HERE. Choose whatever file you want from the list and save it on your PC. NOTE: It would be best for you download the file that corresponds to your current region.
- Extract the contents of the download file and you will get a .tar.md5 file. Save it on your computer and don't extract any further.
- Download Odin 1.85 from HERE. Extract the zip contents and save them on your PC. ODIN is the tool you're going to use in order to flash the new firmware files.
- Power off your Samsung Galaxy S2 now.
- Boot it into Download Mode. It can be done if you press and hold Volume Down, Home and Power buttons simultaneously.
- Launch ODIN program on your computer.
- Connect your device to your PC via USB Cable. ODIN should display a confirmation message telling you that the new device has been 'added!!'. Get to the next step.
- Click the PDA button in ODIN and browse your computer for the '.tar.md5' file you've extracted in step 2. Make sure that the ODIN Default settings are left as they are.
- Click the START button when you're ready for the installation.
- Wait for the install to complete. This process shouldn't take long. Your phone will reboot when all files have been installed and you can disconnect the device from your PC.
- ODIN will say PASS and the phone will continue to boot into normal mode.
- That's it, you've managed to successfully restore your Galaxy S2 to stock Android 4.1.2 Jelly Bean.
These were all the steps that you had to go over and now you can enjoy your brand new stock Jelly Bean firmware operating system.
If you cannot complete the tutorial then you should ask for more help in comments, as I will try to offer you the best solutions and help you unroot your phone successfully.
In case ODIN freezes or it displays a FAIL message, then you should disconnect the Galaxy S2 from PC and remove its battery for 5 seconds. Close ODIN and then re-launch it on your PC. Next, you will need to repeat the entire tutorial starting with step 5. The tutorial should work at your second attempt.
If you don't like the new stock Samsung-edited Android 4.1.2 JB OS and you think that you made a mistake by restoring your device to its original factory settings, then you can easily apply root using some of the guides listed at our 'Android Root' section here.