The method you use depends on whether you are installing a stock Samsung firmware ( .tar.md5 file) or a custom ROM like CyanogenMod ( .zip file).

For the most up-to-date and accurate information, I recommend checking the official Samsung website or contacting their support team.

Upgrading your device from a decade-old operating system to Android 5.1.1 unlocks a host of improvements:

How to Download and Update the GT-I9100 to Android 5.1.1 Lollipop Firmware

For a fully modern OS, or Android 11/12/13 custom ROMs exist for the GT-I9100, though they require repartitioning the internal storage due to the small system partition.

: Back up all user folders, media, and app configurations externally. Custom firmware implementation requires formatting file systems ( /system , /data , /cache ), resulting in total local storage wipeout.

once both installations finish successfully.

Before proceeding, ensure you have completed all the following preparatory steps. Failure to do so can potentially damage your device.

Samsung Galaxy S2 (GT-I9100) Go to product viewer dialog for this item.