Update T-Mobile Galaxy S3 to Jelly Bean Android 4.1 Unofficially With Custom ROM

More Jelly Bean for the T-Mobile Galaxy S3. A new Android 4.1 Jelly Bean based custom ROM has come out for the device – JellyBro – which brings the stock Android 4.1 experience to the phone along with a few features picked from the CyanogenMod 10 and added in for better customization. Jelly Bean as you might know is perhaps the most important Android version ever, specially due to the much smoother interface, as well as other functionality such as advanced voice recognition, offline voice typing, and more, so the more ROMs based on it come out the better.

NOTE: According to the developer, everything in the ROM is working properly, but there still may be bugs and issues here and there as it is a work in progress, and will not contain all the customization from CyanogenMod.

Read on to find out how you can install JellyBro Jelly Bean ROM on your T-Mobile Galaxy S3.


This hack and the guide below are compatible only and only with the T-Mobile Galaxy S3, model number T999. It’s not compatible with other US variants or other devices. Check your device’s model number in: Settings » About phone.


The methods and procedures discussed here are considered risky and you should not attempt anything if you don’t know completely what it is. If any damage occurs to your device, we won’t be held liable.

How to Install JellyBro ROM on T-Mobile Galaxy S3

  1. This procedure will wipe all your apps, data and settings (but it will NOT touch your SD cards, so don’t worry about those). Backup your Apps and important data — bookmarks, contacts, SMS, APNs (internet settings), etc. This Android backup guide would help you.
    Important! Don’t forget to at least make a backup of your APN settings, which you can restore later if your data connection does not work after installing the ROM. Use the backup guide to find out how.
  2. Install ClockworkMod recovery on your phone by following the guide → here.
  3. Download the latest version of the ROM from the official development page.
  4. Download the Google Apps package. This will install apps like Play Store, Gmail, etc. which are not present in the ROM by default.
    Download Gapps  |  Filename: gapps-jb-20120726-signed.zip
  5. Copy the downloaded zip files from step 3 and step 4 to the internal SD card. Do not extract them.
  6. Now, boot into ClockworkMod recovery. To do that, turn off your phone. Then, hold down Volume Up, Home and then the Power buttons together until the screen turns on, then let them go. The phone will boot into ClockworkMod recovery in a few seconds.
    In recovery, use the volume buttons to scroll up/down and the home button to select an option.
  7. Select wipe data/factory reset, then select Yes on next screen to confirm. Wait a while till the data wipe is complete.
  8. Select install zip from sdcard, then select choose zip from sdcard. Scroll to the ROM file on the SD card and select it. Confirm installation by selecting Yes – Install _____.zip on the next screen. The ROM will start installing.
  9. After ROM installation completes, select choose zip from sdcard again, then select the gapps-jb-20120726-signed.zip file to install the Google apps package.
  10. After the ROM finishes installing, select go back then select reboot system now to reboot the phone into CM10.
  11. During the first boot, the phone might reboot a few times before fully booting up, which is normal. If it doesn’t boot even after 15 minutes, remove the phone’s battery, reinsert it, boot into recovery mode as given in step 6, wipe data again as given in step 7, then reboot the phone.
  12. NOTE: If you want to go back to a stock Samsung ROM after flashing CM10, you can use this guide to do so.

JellyBro ROM, based on Android 4.1 Jelly Bean is now installed and running on your T-Mobile Galaxy S3. Visit the official development page for more info and to get the latest updates on the ROM. Share your thoughts on the ROM in the comments.

Also try out the official CyanogenMod 10 (CM10) ROM for the T-Mobile Galaxy S3 → here.


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