The Samsung Galaxy S3 was a hit when it was released, but it soon got older and newer models replaced the flagship. Fast forward to 2015, the hardware of the S3 limits its capability to get updates. And as you would have already guessed, the Galaxy S III (I9300) won’t be getting the Android 6.0 Marshmallow update officially. However, if you are obsessed with the latest Android updates and want to run Marshmallow on your S3, then there’s some good news for you.
You can now enjoy Android Marshmallow on your Galaxy S3 by installing an AOSP custom ROM on it. The ROM has been posted on the XDA forum and has been built with the AOSP port courtesy Haxynox team. Features like touch screen, rotation, Wi-Fi, camera, sound, USB OTG, Bluetooth, etc. are working perfectly in the ROM. But some features like RIL, SD card, screen colors, etc. are not functioning. The ROM has been shared by XDA forum member brianelv, and he hasn’t tested the GPS function yet.
If you own a Samsung Galaxy S3 (I9300) and wish to experience Android Marshmallow on it, you can follow the below-given guide. Remember that the ROM is made only for the I9300 variant of the Galaxy S3, and using it on any other variant might result in a bricked phone. Also remember to backup your data before performing the custom ROM installation.
Guide to Install AOSP Android 6.0 Marshmallow ROM on Samsung Galaxy S3 (I9300)
2. Connect your Galaxy S3 with PC and copy all the downloaded files to the storage of the phone (remember the file location). Now unplug the phone from your computer.
3. Put the S3 into recovery mode. To do this, you can simply use the Quick Boot app from Play Store. Or you can just turn off the phone, and then turn it on again while pressing the Home, Power, and Volume Up buttons together until the recovery mode menu comes up.
4. Once you have successfully entered the recovery mode, make a Nandroid backup of the complete phone data by selecting the Backup option and swiping at the bottom of the screen in order to confirm the backup.
5. After the backup is finished, you need to wipe the data completely. From the recovery menu, select the Wipe option, followed by Advanced wipe. Finally select the Dalvik Cache, System, Data and Cache option. Next, just swipe over the Swipe to wipe option to confirm.
6. Now go back to the recovery menu and tap on the Install option. Navigate to the folder where you copied the CM13 ROM and tap on it. Now swipe over the Swipe to confirm flash option.
7. After the ROM has been installed, repeat the same process to flash Gapps.
8. When the installation has finished, choose the Reboot system option and the phone will restart.
You can now enjoy the Android Marshmallow flavor on your Galaxy S3. In case any errors crop up, check out the XDA development thread for troubleshooting.