So you want to unroot your Galaxy S3 GT-i9300? This unroot method will get you back “completely back to stock” with no trace of rooting. If you are unrooting your Galaxy S3 GT-i9300 for warranty, go ahead and follow the instructions below as no one will be ever to tell you’ve rooted your phone.
For T-Mobile Galaxy S3 SGH-T989, please see How to Unroot T-Mobile Galaxy S3 SGH-T989!
For AT&T Galaxy S3 SGH-I747, please see How to Unroot AT&T Galaxy S3 SGH-I747!
Step 1. First, you will need to go to Samsung-Updates.com and download your desired Galaxy S3 stock ROM. Use the “Region” to find out which Galaxy S3 stock ROM you need and go ahead and download it.
*Note – ALL Galaxy S3 GT-i9300 stock ROMs are compatible with all Galaxy S3 GT-i9300 so you can always re-flash correct one if you flash the wrong one.
Step 2. Once you download the correct stock ROM for your country, go ahead and unzip the zip file. You should find a file that ends in “tar.md5”. This is the stock ROM file you will want to copy over to your Galaxy S3. Go ahead and copy the file over. If you have trouble copying the file because it’s so large, you can try using a micro-SD card and a micro-SD card to SD adapter.
Step 3. You will also need to download Mobile ODIN, Triangle Away app, and Mobile ODIN Kernel pack for i9300. You can find these below:
Get Mobile ODIN
Get Mobile ODIN FlashKernel for i9300 here
Get Triangle Away app here
Step 4. Once downloaded, copy the APK files to your Galaxy S3 and install them up using My Files app.
Step 5. You might have to make sure “Unknown sources” is checked on to install these apps.
Step 6. Once all 3 apps have been install, go ahead and run the Triangle Away app first. This will reset your binary count back to ZERO so no one will be able to tell you’ve ever rooted your phone before. Choose “Reset flash counter” to reset counter.
Step 7. Re-open Triangle Away app and you will notice binary count has been resetted to zero.
Step 8. Next, go ahead and open Mobile ODIN and choose “Open file …” then choose the “tar.md5” stock ROM file you copied over earlier.
Step 9. Choose “Flash firmware”.
Step 10. Make sure to check for MD5 as this is CRUCIAL. Once that’s done, your phone will automatically start unrooting back to a stock ROM.
Step 11. Once done flashing stock ROM, your Galaxy S3 will reboot into Android stock recovery then reboot.
Step 12. Once your phone reboots, you should find yourself on a completely stock Galaxy S3. Your personal settings and apps are still there and if you want to remove them or if you are having trouble after unrooting, you can do a factory reset.
Reboot into stock Android recovery by holding down Volume Up, Center Home, and Power buttons together for about 10 seconds.
Step 13. Once in Android stock recovery, choose “wipe data/factory reset”.
Step 14. Choose “Yes”.
Step 15. Reboot and you will find yourself with the welcome sign just like you saw when you first got your Galaxy S3. Congratulations! You’ve successfully unrooted your Galaxy S3 GT-i9300!
Method is identical for other Galaxy S3s except the files.
For AT&T SGH-i747, Sprint SPH-L710, and T-Mobile SGH-T999, just find stock ROMs for your model and also get the Mobile ODIN FlashKernel for your device but the instructions are the same.