- Download Supreme Custom ROM Firmware package from here to your computer. Once downloaded, connect your device to the computer and place the zip file in device’s external sd card.
- Disconnect the device and download the “ROM Manager” app from the Google PLAY Store and select the option of “Enter into Recovery Mode”. Alternatively, you can also enter your S3 in the recovery mode manually with the help of below mentioned step.
- Hold the Volume Up button + the Home key button (the middle button) and while holding these both keys, press the Power button for turning the device ON in the recovery mode in your Galaxy S3.
- In recovery mode, select “Wipe data/factory reset” & “Wipe Cache partition”. Also, select “advanced” and clear the Dalvik cache too if you are on the custom ROM firmware.
- Now, select “install zip from SD Card” to find for all the zip files present in your Galaxy S3 device, select the placed Supreme Custom ROM Firmware package to initiate the process of firmware update.
- As soon as the update is applied successfully, you will get to see the message of “install from sd card complete”. Now, it will take around 4 -5 minutes for booting the device as it’s the first time the device will be booting after applying the update.
Note: just in a rare case if the device doesn’t boot up or show the home screen then remove the battery and reinsert the same to boot the device again in the normal mode.