Update Galaxy S3 SGH-T999 to Android 4.1.2 Jelly Been SynergyROM

Shaikh Rafia
Posted 4 years ago

SynergyROM, a new custom ROM for Galaxy S3 T-Mobile models, is based on Android 4.1.2. Fully optimized and providing excellent performance, SynergyROM is going to make into your list of favourites. Some of the features of this custom ROM for Galaxy S3 include: Jelly Bean 4.1.2, 23 notification toggles, 4-in-1 reboot menu, fully rotating homescreen, custom boot animation support, multi-carrier support (Verizon, AT&T, Sprint, T-Mobile – all in one), fully working PDroid support, multi-window with free-floating windows (exclusive feature), and much much more.

Follow the prereqs before you update Galaxy S3 SGH-T999 to Android 4.1.2 Jelly Been SynergyROM :

  • Create a backup of all important data in your Galaxy device.
  • Download and install USB drivers for Galaxy S3 in your computer.
  • Enable USB debugging option by pressing Menu > Settings > Applications. Navigate and tap on Developer Options to ensure that USB Debugging is enabled.
  • Make sure that ClockworkMod recovery is installed.
  • Ensure that your Samsung Galaxy S3 carries more than 70% of charge. 

Guide to update Galaxy S3 SGH-T999 to Android 4.1.2 Jelly Been SynergyROM:


Files required: SynergyROM Android 4.1.2 ROM for Samsung Galaxy S3.

  • Connect Galaxy S3 T999 to your computer using USB cable and copy the downloaded file to the SD card of your device.
  • Disconnect the cable and switch off your SGS3 T999. Boot into recovery mode by pressing and holding Volume Up, Down and the Power buttons simultaneously. Use Volume keys to navigate and Power button to select.
  • Now perform a Nandroid backup of your existing ROM to be restored later if this new ROM does not work or you want to move back: Backup and Restore Backup. Go to recovery menu after backup process is done. 
  • Next, perform a full data wipe operation by going to wipe data/factory reset Yes path. Come back to the CMW recovery main menu and select wipe cache partition. When done, tap on Advance wipe Dalvik Cache to wipe Dalvik cache data too.
  • After the wiping operation, select install zip from sdcard and choose zip from sdcard. Locate the ROM firmware file from SdCard. Tap on yes to confirm installation and wait for the ROM installation process to finish.
  • Navigate to +++++Go Back+++++ and select reboot system now. Wait for the SGS3 to boot in to the new SynergyROM based on Android 4.1.2 for T-Mobile T999 models.

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