AT&T Samsung Galaxy S3 shipped with Android 4.4.4 KitKat version, but you know it’s not going to get Android 5.0 Lollipop update ever because Samsung is not supporting this smartphone. But today I’m going to tell you about a new custom ROM with Android 6.0 Marshmallow user interface and features. This custom ROM has all the features of Android 6.0 Marshmallow with some extra features added by Cyanogen team for better computing performance and improved battery performance. If you want to get rid of that bulky and laggy Touch Wiz UI, then you should try this custom ROM, and I’m sure you’ll love this custom ROM.

Here is everything that one needs to update the AT&T variant of the Samsung Galaxy S3 smartphone with an unofficial Android 6.0 Marshmallow update with a custom ROM:


Things To Remember:

  • First You need to root your phone first then install a custom recovery on it.
  • Make sure that you backup all your data before installing a custom ROM, any smart phone manager on your PC can do this.
  • Charge your phone to at least 70% battery so it won’t go off during the installation.
  • This custom ROM and installation guide is only for AT&T Samsung Galaxy S3 only do not try to install this custom ROM on any other Samsung or Android variant because it may damage your device badly.

Steps to install Android 6.0 Marshmallow on AT&T Samsung Galaxy S3:

  1. Download the custom ROM from here.
  2. Download Google Apps from here.
  3. Connect Your phone to your PC and transfer both the zip files to yours.
  4. After that unplug your phone and reboot it into the recovery mode immediately.
  5. When in recovery tap on the wipe and confirm to wipe all the internal system memory, cache and Dalvik cache.
  6. After that tap on install, select the custom ROM zip file and confirm to install the ROM on your phone.
  7. Repeat the step #7 to install Google apps also.
  8. After installation tap on “Reboot” and then “System” to restart the phone.
  9. Wait for some time and you will see a setup screen to set up your phone for the very first time.
  10. And if you have any queries about the installation or if you want to report any broken links, then please tell us using the comment section below.

Android Lollipop

In conclusion, that is how to install Android 6.0 Marshmallow software updates on the AT&T Samsung Galaxy S3 by making use of a custom ROM instead of the stock ROM. A custom ROM usually voids the warranty and any device that has Samsung Knox security will not be getting that warranty back again, so make sure you know what you are signing up for before starting.