Developers over at XDA have released a number of customizations for the Galaxy S III. Mostly, the custom ROMs and other tweaks that have been released are targeted at separate variants of the device (Verizon, T-Mobile or AT&T), and rarely we get to see a ROM that’s meant for all models. XDA Developers member itsmikeramsay brings something new to the table in the form of Illusion ROM, which is meant for all models of the handset.
The ROM brings CM10.1 and the goodness of firmware 4.2.1 Jelly Bean. However, there are some issues with the shortcuts on the lockscreen and the camera.
Before proceeding onto the instructions, note a few things first. The guide will work on Verizon S3 SCH-i535, AT&T S3 SGH-i747 and T-Mobile S3 SGH-T999. Apart from these three models, the guide may damage other devices. Charge the battery of the variant you’re using at a proper level. Disable any softwares on your PC that can prevent the installation of files. Create a backup of important files (read this) and please note the tutorial has to be followed at your own risk, as we won’t pay any damages if anything goes wrong.
Tutorial
Step 1: Root your variant and install ClockworkMod recovery on it. Here are some helpful posts:
ClockworkMod SGH-T999
Root SGH-T999
root and recovery SCH-i535
ClockworkMod SGH-i747
Step 2: Download the Illusion ROM for AT&T, Verizon or T-Mobile S3.
Step 3: Download the Gapps package.
Step 4: Copy the downloaded ROM file (depending upon your variant) and Gapps package to the phone’s internal memory card.
Step 5: Switch off the device and restart by holding Power, Volume + and Home keys to boot into CWM recovery.
Step 6: Create a Nandroid backup of the current ROM by selecting Backup & Restore > Backup.
Step 7: Choose wipe data/factory reset and confirm the action. Next, choose Mounts & Storage > Format/system. Now choose Wipe cache and prompt the action. Lastly, choose Advanced > Wipe Dalvik Cache and allow for the action.
Step 8: This step is to be followed two times (for installing ROM and Gapps package). Select Install zip from internal sd > Choose zip from internal SD. Now select the ROM file and go for Yes. Repeat and select Gapps > Yes.
Step 9: After both ROM and Gapps are installed. Return to the main menu and select Reboot system now.
Hurray. You’ve flashed Illusion ROM on Verizon Galaxy S III SCH-i535/AT&T SGH-i747/T-Mobile SGH-T999. Feel free to leave comments. (via: XDA)