Android 4.1 is launched and already ported to Samsung Galaxy S3 but it has lots of bugs and you will be missing lots of SGS3 apps. Jelly Bean update will be releasing for AT&T SGS3 but it would take atleast 2-3 months. The best ROM you can port to Samsung Galaxy S3 is CyanogenMod 9 based on AOKP ICS. This ROM has few bugs but will be resolved very soon.
Alert/Warning: Installing custom requires rooting your device and installing custom recovery. This voids warranty, but you can reclaim warranty by installing Stock firmware and unrooting your device.
Compatibility: This method is compatible only with the AT&T Galaxy S3 model SGH-i747 and no with other variations. Please confirm the model before proceed in Settings > About phone.
The data on your AT&T Galaxy S3 SGH-i747 must be backed up before following the mentioned tutorial. This will be very helpful for you to restore your data back to its previous state. The list of important data for backup is below – Images, Music, Videos, Call Logs, Contacts, SMS, APN & MMS Settings.
You need to disable the security suites on your AT&T Galaxy S3 SGH-i747, for which you need to follow the path Settings > Security > Mark “Unknown sources” and check whether it is ticked or not. Then, charge your device battery to 50% or more, just to ensure that it is won’t turn off during the process. After that, enable the USB Debugging option to through the path ‘Settings > Applications > Development > USB debugging’.
Here we go; you can install CyanogenMod 9 (CM9) on your AT&T Galaxy S3 SGH-i747 but before that please root your AT&T Galaxy S3 and install the ClockworkMod Recovery on it.
How to Update CM9 on your AT&T Galaxy S3 SGH-i747
- Download the latest CM9 from the official development page.
- Also, download Google Apps Package (Filename: gapps-ics-20120429-signed.zip)
- Once you have completed the download, place those zip file to the root of the SD card or internal memory.
- Now, turn off your AT&T device to boot into the ClockworkMod recovery just by holding the Volume Up + Home buttons, then press the power button while keep holding them. When screen appears then let them go.
- When it get into the recovery mode use the Volume Up / Down button to scroll and Home button for select.
- Here, you need to clear cache on your device by select ‘Wipe data/factory reset’ & ‘Wipe Cache partition’ options.
- You need to select ‘install zip form sdcard’ and then ‘choose zip from sdcard’ to get in the list where you can find both the downloaded zip file. First select the zip file for ROM and confirm your selection. Then, repeat the same with gapps-ics-20120429-signed.zip file. Similarly, confirm the installation by tapping on ‘Yes’.
- Once the installation is completed, choose the ‘+++Go Back+++’ option and then select ‘reboot system now’ to reboot your phone with CyanogenMod 9 (CM9) on it.
You have successfully installed CM9 nightly ROM on your AT&T Galaxy S3 SGH-i747.