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Install Unofficial CM 11 Android 4.4 custom build for AT&T Samsung Galaxy S3

AT&T Galaxy S3 can now be updated to Android 4.4 using a custom ROM that is based on unofficial CyanogenMod 11. Use this tutorial and learn how to successfully update your device without bricking it. Note that this is not an official update released by Samsung nor by AT&T, so you should install it at your own risk.

CyanogenMod 11 Nightlies will arrive soon but, until then you can test experimental builds based on it so that you’ll form an idea and see how your Galaxy S3 works with the latest Android 4.4 builds. If you want to learn more about this experimental build, take a look at its dedicated XDA thread here.

Since this is a test build of CM 11 KitKat you should expect to find bugs and errors while using it. At the moment the WiFi tethering isn’t working. Also, Netflix doesn’t display correctly videos on the smartphone, but it will work via Chromecast. Use the comments section for other bugs that you will find while testing CM 11 Experimental build.

Read the preparation guide below in order to make sure that you successfully update your AT&T Galaxy S3 with Unofficial CM 11:

  • Use this post only with the Samsung Galaxy S3 AT&T.
    – don’t attempt to update any other smartphone with the files you find in this article.
  • This guide works with AT&T Galaxy S3 that’s rooted, factory unlocked and running the latest CWM Recovery image.
    – if your device doesn’t meet all these requirements then you shouldn’t attempt to flash the custom ROM files.
  • In the tutorial post of this post you will find the ‘wipe data/ factory reset’ step, do not skip it.
    – if you skip factory reset, then the Galaxy S3 AT&T will not boot with the new ROM.
    – Factory Reset wipes all data from system partition, while the internal and external storage card won’t be affected by this process.
    – this step is found in the tutorial.
  • Backup data from applications that are installed on your device using Helium app from Google Play Store here.
    – do not use the Titanium Backup tool, as you won’t be able to restore data after installing KitKat ROM.
  • Backup SMS and APN Internet Settings using the following tools for Android: SMS backup & restore | APN Settings Backup & Restore.
  • Use your default Gmail account to sync all your Contacts details and People info.
    – in case you don’t know how to do it, then you can learn using the info listed here.
  • Enable USB Debugging from Developer Options.
  • In the ‘how-to’ part of this post you will find the NANDROID Backup step that teaches you to save the installed ROM.
    – this will set a restore point for your phone and you can use it in case the new ROM doesn’t boot in normal mode.
  • Read the entire post, don’t skip any steps and use the comments field to ask for more help in case you cannot complete the installation.
  • Check the device’s battery charge level and make sure that these are over 50%, so that the AT&T SGS3 won’t switch off in the middle of the updating process.

How to Install Unofficial CM 11 Android 4.4 custom ROM for AT&T Galaxy S3:

  1. Download the Unofficial CM 11 KitKat ROM zip from here.
  2. Download Gapps for this particular custom ROM from here.
  3. Connect your AT&T Galaxy S3 with your computer and then transfer both zip files to your smartphone’s internal storage.
    – after the files are moved, disconnect the phone from PC.
  4. Power off your AT&T Galaxy S3 completely.
  5. Boot the device in CWM Recovery Mode.
    – if you don’t know how to do it you should use the info listed in this post here.
  6. First thing that you need to do is to create a full NANDROID Backup of your currently installed ROM:
    – select ‘backup and restore option’, save the file on the internal or external storage and confirm the process.
  7. Next, select ‘wipe data/ factory reset’ and confirm this process.
  8. Now, go to Mounts and Storage and select ‘format’ then select ‘system’. Continue to the next step when done.
  9. Install the custom ROM by selecting ‘install zip from sdcard’, then ‘choose zip from sdcard’.
    – find the Unofficial CM11 zip file and confirm its installation.
  10. After all ROM files are flashed you need to reboot the phone and complete the CyanogenMod Setup.
  11. Next, reboot in CWM Recovery Mode and select again ‘install zip from sdcard’, then ‘choose zip from sdcard’. Flash the Gapps zip.
  12. When the installation is complete, reboot your phone in normal mode.
  13. Enter your Google Account info and then take control over your device.

Test all the new features and functions that have been installed along with the Unofficial CM 11 on your AT&T Galaxy S3 device. If you’re having problems with the installation process, then you should ask for more help in comments and we will gladly come to your aid.