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Flash Android 4.1.2 Jelly Bean UCMD8 Update for the AT&T Samsung Galaxy S2 I777

Samsung and AT&T have made available the first build of Android 4.1.2 Jelly Bean for the AT&T Galaxy S2 phone. Use this tutorial to learn how to successfully update your device manually without using the KIES software. Also, this guide will work AT&T Galaxy S2 owners who didn’t receive the official update files on their KIES software.

In order to successfully install the update, you will first need to read the preparation guide below:

  • Use this tutorial only with the AT&T variant of the Samsung Galaxy S2 with I777 as the default model number.
  • Don’t try to flash the files you find here on any other Galaxy S2 variant because you will end up bricking it.
  • If your phone is rooted, then the update process will revoke root access and it will be restored to stock status. The warranty for your device will also be restored. This info is available only for users who customized the OS of their device by rooting it or installing any other custom files.
  • Also, users who are currently using a custom ROM for their AT&T Galaxy S2 will be forced to factory reset the device after the update is complete.
  • Download and install the Samsung USB Drivers for your computer. Without these you cannot connect the phone with your PC.
  • Using this tutorial might remove all data from your smartphone, which is why it would be better for you to backup all the important data before starting the update process.
  • Sync your Contacts info with your Gmail account so that you won’t lose any important Contacts data or phone numbers.
  • Enable USB Debugging from the phone’s Developer Options section.
    > NOTE: after the update is installed, the Developer Options menu will be hidden and you will have to re-enable it by opening Settings and then find ‘Build Number’ section. Tap ‘build number’ 7 times for the Developer Options menu to re-appear on your phone’s Settings menu.
  • Make sure that there is no antivirus running on your computer while installing the new OS.
  • For the updating process you will need to use the ODIN program, which is why your computer should have all the antivirus programs disabled. Such security tools will interfere with the Jelly Bean UCMD8 installation and the update will fail.
  • Make sure that there is enough power left in your device’s battery. The charge levels should be over 50% to make sure that the update will complete without problems.
  • This is a guide for advanced Android users.
  • You cannot held us responsible in case something goes wrong and you lose data or you brick your phone in the process.
  • Read the entire post and make sure that you won’t skip any steps that I have listed below.

Now that you know all of the above, continue to the next part of this post.

How to update AT&T Galaxy S2 I777 to official Android 4.1.2 Jelly Bean UCMD8 firmware:

  1. Download the I777UCMD8 firmware zip from HERE.
  2. After the download is complete, extract the zip contents and you will get a file named I777UCMD8_I777ATTMD8_ATT.tar.md5. Don’t extract any further than that.
  3. Download ODIN 3.07 from HERE. Extract its contents and save them in a single folder on your PC desktop screen.
    > in case Odin 3 v3.07 doesn’t work, then you can try to use Odin3 v3.04 (here) or Odin3 v.1.85 (here).
  4. Now you need to power off your smartphone.
  5. Boot the device into Download Mode. When the phone has entered the Download Mode you can continue to the next step.
  6. Launch ODIN exe.
  7. Connect your smartphone with your computer right now.
    >Odin will say ‘Added!!’ and that means that the two systems have been successfully connected.
    > In case Odin doesn’t recognize your phone, then you should try to plug it into a different USB port or re-install the USB Drivers.
  8. When everything is set, you need to click the ‘PDA’ button.
  9. Browse your computer for the I777UCMD8_I777ATTMD8_ATT.tar.md5 file and load it into ODIN.
    > don’t edit any other Odin default settings, but make sure that the ‘Re-partition’ option is disabled.
  10. When you’re ready, click ‘START’ button and wait for Odin to install the Android 4.1.2 Jelly Bean Update files for your AT&T Galaxy S2 phone.
  11. After the installation is complete, your phone will reboot and you can unplug it from computer when the Samsung boot animation screen appears.
  12. Wait several minutes for all files to be successfully loaded and then take control over the phone.
  13. These were the steps that you had to take, test all the Jelly Bean 4.1.2 features and tell us in comments if the the Galaxy S2 AT&T performance has been improved by the update.

These were all the steps that you had to take in order to install the latest and first build of Android 4.1.2 JB for At&t Galaxy S2 smartphone.

If the installation was completed successfully, then you can close this tutorial and start testing your new operating system features. For users who encountered problems during the installation, read the notes below and you might find a solutions.

NOTE 1: in case ODIN freezes, it displays the Fail alert or it doesn’t complete the tutorial for any other reason, then you should disconnect the phone from PC. Close ODIN and remove the phone’s battery. Re-insert the battery after 5 seconds passed and then repeat the entire tutorial once again starting with step 3. This time you might want to use another Odin version.

NOTE 2: if ODIN completed the installation, but the AT&T Galaxy S2 doesn’t want to boot with the new Jelly Bean 4.1.2 UCMD8 firmware, then you will be forced to apply a ‘factory reset’. This will get rid of all contents from your device’s system partition, but it will force the device to boot with the new original ROM. Here’s how to do that:

  • power off the phone completely.
  • boot into Recovery Mode.
  • select ‘wipe data/ factory reset’ and confirm.
  • wait for the ‘factory reset’ process to complete successfully.
  • get back to the main Recovery Mode menu and select ‘reboot system now’.
  • wait several minutes for all the files to be loaded and for your device to boot the I777UCMD8 Jelly Bean home screen.

If you have any other questions, use the comments field below.

If you want to root this new firmware update, then you should check back this web page in order to find a working ‘how-to’ guide.