How to Flash UCUEMJ2 Jelly Bean 4.3 leaked firmware on Galaxy S3 T999

T-Mobile Galaxy S3 T999 is going to sprout many new and interesting things after you see what we have for you! And that is: a guide on how to swiftly and smoothly upgrade your phone to UCUEMJ2 Android 4.3 Jelly Bean leaked firmware. In fact, this custom file was made for the I474, but is compatible with this model, too.

What you get in exchange for this firmware is the possibility to make the best out of your handset by installing different custom ROMs, apps and so on. The new ported firmware allows you to also enjoy a better battery unit and a superior performance delivered by your phone. As soon as you agree that this is the ROM you’ve been waiting for, consider this tutorial and all the steps in it.


Before we disclose the steps needed for the upgrade, you should know that there are certain pre-requisites we ask you to follow. Here you go:

  • charge your phone’s battery;
  • turn on USB Debugging;
  • download the new (which comes already rooted, whose SELinux is turned off and KNOX is removed) on your laptop;
  • download Galaxy S3 Modem on the same device, from ;
  • install the dedicated Galaxy S3 KERNEL along with Root Fix on the notebook, from ;
  • flash USB drivers for this phone on your notebook or comp;
  • create backups using this method or a similar one.Galaxy-S3-SGH-T999

Step-by-Step Installation Guide

After all of the compulsory requirements above are dealt with one by one, you can finally consider the update steps we prepared for you below.

  1. This is the first step we have for you: plug your Samsung T999 to the laptop after you are done with the download of the files (Modem, Root Fix and Kernel ones, to be precise) from our pre-requisites. Which files must be sent over to the phone’s SD card root from your laptop’s desktop.
  2. The handset needs to be turned off now and then you should enter it in Recovery Mode like shown here: press and hold, at the same time, Power + Volume Up +Home and, when you spot the logo of the manufacturer, stop.
  3. We now need you to apply a factory reset by installing the update file first and then following these steps in case TWRP is installed on your device: tap “Install”, then the StockMOD ROM T999
  4. To apply a factory reset if you run the CWM, you should choose Install zip from SD card, opt for Choose zip from SD card and then tap StockMOD ROM .zip to flash it.
  5. Now move on to the installation of the Galaxy S3 Modem file. Should there be the CWM, you have to tap Install zip from SD card, select Choose zip from SD card, find and confirm the latter’s flashing.
  6. In the case of the TWRP, all you need to do is this: after you tap Install, you have to get the same Modem .zip file and tap on it to flash it on the smartphone.
  7. [sc name=”banner-jos”]Now apply the other two files: the Root Fix and then the Kernel. Do it by looking at these steps should your phone own the TWRP: as soon as you are done with tapping Install, you should search and then click it to have it installed.
  8. If the CWM is running on your handset, you need to click on the option called Install zip from SD card, select, next, Choose zip from SD card and confirm the flashing of the Insecure Kernel after you find it.
  9. Next up: return to the Recovery screen. Your smartphone will have to be restarted next, so choose the appropriate option. After you are done, the Jelly Bean 4.3 UCUEMJ2 ported firmware will run on your Galaxy S3 T999 T-Mobile.

  • Geek Guy

    This custom ROM is compatible with similar devices, from Verizon, for example? I want to test it but I am not sure if will work on my phablet. Can you help me with an advice? Thank you!