Update Samsung Galaxy S3 to Android 4.1.2 with Slim Bean JZO54K

Just recently Android developers came up with another custom firmware update for Galaxy S3 to Android 4.1.2 Jelly Bean. This could turn out to be really useful in the lack of an official upgrade from Samsung.The following update is only available for Galaxy S3 GT-I9300 models (Check Settings, About Device, Model Number) so if you are the owner of a different device you should not go on any further.Just to remember you, any modifications you bring to the original firmware by installing custom ROMs is putting your phone in danger of bricking. This means you continue on your own risk.Before you go on with the installation,  you should make sure your Galaxy S3 meets the necessary requirements:- Install as USB drivers for your Windows OS- In order to save all your personal data do a backup of your phone- Go to Settings, Developer options, USB debugging and check it.- In order for the update to work, you will need a rooted Galaxy S3. If your phone is not rooted, you can check our tutorial on how to root a Samsung Galaxy S3 device. This rooting method will also include ClockworkMod, which is also required to proceed with the 4.1.2 Slim Beat Update.- The last step is to do a Dalvik Cache wipeHow to update Galaxy S3 to Android 4.1.2 Slim Beat JZO54K?Step1: Download the Android 4.1.2 JZO54K update from here.Step2: Download the Google Apps package.Step3: Now connect the GT-I9300 to the USB port and copy the files you just downloaded on the root folder of the SD card.Step4: Unplug the GT-I9300 and turn it off. Enter ClockworkMod Recovery Mode ( Hold Volume Up, Home and Power until it enters recovery mode).Step5: While in Recovery press <Wipe data/factory reset> and < Wipe Cache partition>.Step6: Now press <install zip from sdcard> and select <choose zip from sdcard> in the Clockworkmod menu. Select the JZO54K update package and the Google Apps package.Step7: Wait 4, 5 minutes until the updates are installed. Press<Go back> and <Reboot System now>. This should restart the device in normal mode. This reboot usually takes longer but that's normal.Important: If the device gets stuck at any point, just restart the phone by pulling the battery and start all over again.You now have Android 4.1.2 Slim Beat JZO54K installed and ready to roll.