How to Flash Jelly Bean onto your T-Mobile Galaxy S3 (SGH-T999)

So last week we brought you the latest leak of the official Jelly Bean update for the T-Mobile Galaxy S3, today we are going to tell you how to flash it. Now if you’ve flashed any other ROM on your Galaxy S3 you should be fine. If not continue below.

Requirements

• Rooted and unlocked T-Mobile Galaxy S3 (SGH-T999)
• Custom Recovery either Clockworkmod or TWRP (I recommend Clockworkmod)

Warning

• OMG!Droid is not responsible for any harm caused to your T-Mobile Galaxy S3
• This is for the T-Mobile Galaxy S3 (SGH-T999) only

Instructions

1. Copy SGH-T999_T999UVDLI3-OTA-T999UVALH2_TMB_332312338.zip to your phone’s internal SD card.
2. Switch off your mobile phone.
3. Reboot your phone into ClockworkMod Recovery Mode (or whatever custom recovery you’ve chosen to install). You can do that by pressing and holding down the Volume Up key, Home button (middle key), and the Power button simultaneously until recovery boots.
   • NOTE: Once in recovery, use the Volume keys to navigate and the Home button to select an option. Unless you are using Touch CWM or TWRP.
4. Create a NANDroid backup of your current ROM. Select Backup and Restore and select Back upon the next screen.
5. Select Wipe Data/Factory Reset and confirm the action on the next screen.
6. Select Wipe Cache Partition and confirm the action on the next screen.
7. Go back to the main menu and select Advanced. From there, select Wipe Dalvik Cacheand confirm the action on the next screen.
8. Return to the main menu and select Install ZIP From SD Card.
9. Select Choose ZIP From SD Card and locate SGH-T999_T999UVDLI3-OTA-T999UVALH2_TMB_332312338.zip file. Confirm the action on the next screen to flash the ROM to your mobile phone.
10. Go back to the main menu and select Reboot System Nowto restart your phone.
11. To revert to your previous ROM, reboot your phone into ClockworkMod Recovery and select Backup and Restore.On the next screen, select Restore to install your previous backup ROM.

Enjoy your Galaxy S3 with Jelly Bean goodness. If you have any problems feel free to post them in the comments below and we’ll do our best to assist you.

Source: XDA