Yeah we know you want some Jellybean, but if history of Android has taught us one thing that is to root your phone and flash a custom ROM on that bad boy. We know updates don’t come out as they should. Manufacturers take months to test them, then our carriers take even more time to test them before we can get our hands on them. So what we are showing you today is how to install a ROM from developer drewgaren over on XDA Developers. He’s taken the leaked Jellybean OTA’s for the T-Mobile Galaxy S3 and ported them over to the AT&T version, and has just pushed out Milestone 2.
So let’s get started
OMG!Droid is not responsible for any harm caused to your precious Galaxy S3 during this process.
This tutorial is only for the AT&T Galaxy S3, model number SGH-I747. Trying this on any other Galaxy S3 could result in bricking your device
Rooted AT&T Galaxy S3 with a custom recovery installed.
Copy the Jelly Bean ROM package to the internal SD card of your phone. Or external SD card if you have one.
Reboot your device into Clockworkmod recovery, or whatever recovery you are using. To do this, press and hold down the Volume Up, Home, and Power buttons until the phone boots into recovery.
Make a NANDroid backup of your current ROM. To create a backup, go to Backup and Restore and select Backup.
Select Wipe data/factory reset and confirm the action on the next screen. Wait for the process to finish.
Select Install ZIP from SD card.
Select Choose ZIP from SD card and navigate to the ROM file. Select the file and confirm the action on the next screen to start installing the ROM on your phone.
Once installation of the ROM is done, select Go back and select Reboot system now. This will reboot your phone to the newly installed Jellybean ROM.
Congratulations you now have Jelly Bean and Touchwiz on your Samsung Galaxy S3. As always if you encounter any problems, go ahead and leave a comment below and we’ll do our best to assist you. Also let us know how the ROM works out for you.