We shared with you CyanogenMod 12.1 custom firmware based on Android 5.1 Lollipop for HTC's 2014 flagship. The Lollipop custom ROM is now also available for Samsung Galaxy S3 I9300. Here is how to update Galaxy S3 I9300 to Android 5.1 Lollipop based CM 12.1.

Prerequisites to update Galaxy S3 i9300 to Android 5.1 CM 12.1:

Create abackupof all important data in your Galaxy device.

Download and install USB drivers forSamsung Galaxy S3in your computer.Enable USB debugging option by pressingMenu>Settings>Applications. Navigate and tap onDeveloper Optionsto ensure thatUSB Debuggingis enabled.Make sure that recovery tool likeClockworkMod recoveryis installed.Ensure that your Samsung Galaxy S3 i9300 carries more than 80% of charge.

Update Galaxy S3 i9300 to Android 5.1:

Files required:download theCM 12.1 Android 5.1 Lollipopcustom firmware fromhere; also download theGoogle Apps. Save both files on PC.

Here are the steps to update Galaxy S3 i9300 to Android 5.1 based CyanogenMod 12.1:

Connect your SamsungGalaxy S3 I9300to your computer using USB cable and copy the downloaded files to the SD card of your Galaxy device.Disconnect the connection with PC and turn your GalaxyS3 off.Boot in to custom recovery mode: press and holdVolume Up, Downand thePowerbuttons simultaneously untilSamsunglogo shows up. Leave the keys for half a second and hold again. UseVolumekeys to scroll andPowerbutton to select -alternatively you can useQuick Boot appto reboot your Android device in recovery mode.Now perform Nandroid backup of your current ROM: selectBackup and Restore>Backup. Go back to main recovery menu after backup process is done -very important step to restore back to current OS.Data wiping tasks: selectwipe data/factory reset>Yes. It will take a few minutes; once done, selectwipe cache partition.Next tap onAdvance>wipe Dalvik Cacheto wipe Dalvik cache data too.Selectinstall zip from sdcardfollowed bychoosezip from sdcard. Locate the Android 5.1 based CM 12.1 custom ROMfile copied earlier and select it. Tap onyesto confirm installation and wait for the ROM installation to be completed.Once installation process is finished successfully, repeat the above step but chooseGAppsfile instead to install the Google apps package on your SGS3 I9300.Return to main recovery menu now and selectreboot system nowto boot up into the latest CM 12.1 Android 5.1 Lollipop custom firmwareforSamsung GalaxyS3. It will take a bit of time during the first boot, so kindly be patient.Ta da! Enjoy Lollipop on Galaxy S3.

How to restore:If you want to return to previous OS on your SGS3, boot intorecovery, selectbackup and restorethen restore your previous ROM by selecting it from the list.