Flash Leaked Android 4.3 UCUEMJ2 Jelly Bean ROM for AT&T Samsung Galaxy S3

Android 4.3 Jelly Bean Official OTA Update leaked for AT&T Galaxy S3, Note 2, Galaxy S4 and Galaxy Active

The leaked Android 4.3 Jelly Bean firmware can now be flashed on your AT&T Galaxy S3 using the instructions that I have listed in this post. Read the entire article and you will be able to flash all the files without any problems. Remember that this tutorial works only with the AT&T SGS3 phone and that it is not recommended for you to flash it on any other device.

Android 4.3 Jelly Bean stock UCUEMJ2 build has been leaked, which means that the final OTA Update is not very far away. However, users who want to test the latest Android 4.3 features can flash the leaked ROM.

In this post you’ll find two versions of the ROM, the first one is the Unmodified UCUEMJ2 Jelly Bean 4.3 version which is full stock, no root and it has the KNOX security enabled along with SE-Linux.

The second version is a modified UCUEMJ2 Jelly Bean 4.3 ROM that is pre-rooted, KNOX is disabled and SE-Linux is disabled too.

Choose whatever version of the leaked ROM you wish to flash, as you will find both guides listed below. Before starting the installation take a look at the preparation guide below:

  • Use this post only for the Samsung Galaxy S3 AT&T wiht model number SGH – I747.
  • Do not attempt to use this tutorial for any other Android smartphones.
  • The AT&T Galaxy S3 AT&T you’re about to update has to be on stock firmware.
  • Your device has to be rooted and factory unlocked.
  • Also, CWM or TWRP Recovery has to be installed on it, as the custom Recovery Mode will be used to flash the leaked ROM.
  • Since this installation might delete all data from your phone, then you should backup all the important files.
  • Enable USB Debugging for your phone from Developer Options menu.
  • Make sure that your phone’s battery has enough power left before it completely switches off. At least 70% charge level is required.
  • This is a guide for advanced Android users and you shouldn’t attempt to flash this ROM on your phone in case you’re a beginner, as you risk bricking the phone.
  • You cannot held us responsible in case you brick the phone or lose any data files in the process.
  • If you have any problems completing the installation, then you should ask for more help in comments. Make sure to leave a detailed comment so that we will be able to come up with a viable solution for whatever problem you’ve encountered.

Now that you’ve read all of the above, continue to the next part of this post.

How to install leaked Android 4.3 UCUEMJ2 Jelly Bean Unmodified ROM for Samsung Galaxy S3 AT&T:

  1. Download the unmodified UCUEMJ2 Android 4.3 ROM from here.
  2. Download the Bootloader/ Modem zip file from here.
  3. Connect your phone to your computer, then move the downloaded zip files to your phone’s internal storage.
    – do not extract the archived contents.
    – after the files are copied, disconnect the device from PC.
  4. Power off your smartphone now.
  5. Boot the Galaxy S3 AT&T in custom Recovery Mode.
    – remember that both files are supported by this tutorial.
    – if you don’t know how to boot Recovery Mode, then you should use this post here.
  6. First thing that you need to do is to apply a Factory Reset.
    – CWM: select ‘wipe data/ factory reset’. Confirm the process.
    – TWRP: press Wipe, then swipe to confirm factory reset.
  7. Next, you need to flash the bootloader / modem zip:
    – CWM: select ‘install zip from sdcard’, then ‘choose zip from sdcard’ option and find the ‘d2att_I747UCUEMJ2_bootloader_modem.zip’ and confirm its installation.
    – TWRP: press Install, then find the ‘d2att_I747UCUEMJ2_bootloader_modem.zip’ file. Confirm the process.
  8. Now, after the modem has been flashed you will need to install the Unmodified stock UCUEMJ2 firmware.
    – CWM: select ‘install zip from sdcard’, then ‘choose zip from sdcard’. Find the ‘d2att_I747UCUEMJ2_stock_noroot.zip ‘. Confirm the install process.
    – TWRP: press Install, find the ‘d2att_I747UCUEMJ2_stock_noroot.zip ‘ then confirm the process.
  9. After both zip files are installed, then you should return to the main recovery screen.
  10. Reboot your phone now.
  11. Wait for the first boot process to complete, then you should enter your Google Account info to take control over your device.

These were all steps you had to take in order to successfully flash the unmodified leaked Android 4.3 ROM for your smartphone.

How to flash leaked Android 4.3 UCUEMJ2 Jelly Bean Modified ROM for Samsung Galaxy S3 AT&T:

This guide will teach you how to flash the modified, rooted and No KNox leaked UCUEMJ2 Android 4.3 firmware on your device. Don’t skip any steps that I’ve listed below.

  1. Download the ROM file from here.
  2. Download the bootloader / modem file from here.
  3. Connect the phone to your PC, then copy both files on your smartphone’s internal storage.
    – do not unzip the files.
    – after the files are moved, then you should disconnect the device from PC.
  4. Switch off your AT&T Galaxy S3 completely.
  5. Boot the phone in custom Recovery Mode:
    – both CWM and TWRP Recoveries are supported by this tutorial.
    – recovery mode is booted by pressing Volume Up, Home and Power all at the same time.
    – if you cannot boot Recovery, then use the info listed here for extra instructions.
  6. First, Factory Reset your smartphone:
    – CWM: select ‘wipe data/ factory reset’. Confirm.
    – TWRP: press Wipe, then swipe to confirm the process.
  7. Return to the main custom Recovery Mode screen and now you can flash the bootloader / modem file:
    – CWM: select ‘install zip from sdcard’, then ‘choose zip from sdcard’. Find the ‘d2att_I747UCUEMJ2_bootloader_modem.zip’ file. Confirm the installation.
    – TWRP: press Install, then find the ‘d2att_I747UCUEMJ2_bootloader_modem.zip’. Confirm the installation by swiping the blue button at the bottom of the screen.
  8. Now you can install the modified ROM.
    – CWM: select ‘install zip from sdcard’ again, then ‘choose zip from sdcard’. Find the ‘d2att_I747UCUEMJ2_root_noknox.zip’ file. Confirm.
    – TWRP: press Install, find the ‘ d2att_I747UCUEMJ2_root_noknox.zip’ file and confirm the process.
  9. After the installation is complete, return to the main custom Recovery screen.
  10. Reboot your phone now in normal mode.

These were all the steps that you had to follow in order to successfully flash all the new Android 4.3 leaked ROM files for your AT&T Galaxy S3 smartphone. If you have any other questions, then you should ask for more help in comments.

Also, if you need extra info, then you can follow this XDA thread link here and get it straight from the developer who leaked the firmware.

  • Eli Burns-Irvin

    Hey guys, great walk through. At the beginning when pointing out that the owner of the phone is responsible for the risks of the flashing process, you used “held” instead of “hold”. Obviously not a big deal, just letting guys know. Thank you again!

  • Stephen Austin

    For anyone wanting this update and are worried about problems I have found almost none except a few apps need to be uninstalled then reinstalled!! And some of my downloaded pictures were gone!! The camera ui didn’t change as this is a leak not official however my phone has gotten considerably faster and games play much smoother this update has breathed new life into my AT&T Galaxy S3 but if you’re not sure how to do it would be best to wait until official launch on possibly November 13!! As it will have the new camera update and fixed those minor bugs. When I did Quadrant I scored 6,206 compared to my average before the update of around 5,700 which makes perfect sense due to the huge increase in Gaming Performance!! Thank you samsung the long wait was definitely worth it!!!!!!!!!

  • Ernesto Molina

    not wanting to install the ‘d2att_I747UCUEMJ2_bootloader_modem.zip’ file.

  • zikril

    why fail to install d2att_I747UCUEMJ2_bootloader_modem.zip?

  • Pingback: Android 4.3 Jelly Bean Leaked for AT&T’s Samsung Galaxy S3, Samsung Galaxy S4, Samsung Galaxy Note 2 and Samsung Galaxy S4 Active()

  • Pingback: Install Ported Android 4.3 UCUEMJ2 Jelly Bean ROM for T-Mobile Samsung Galaxy S3 T999 (No KNOX and Rooted ROM)()