The international LTE version of Samsung Galaxy S3, model number GT-I9305, was launched with Android 4.1.1 Jelly Bean and later upgraded to the latest Android 4.1.2 software.
Samsung is yet to roll out an Android 4.2.2 official update, but there are several versions of the latest Jelly Bean software for the S3 LTE, thanks to custom builds released by Android developers community. To install custom firmware, the device needs root access and a custom recovery pre-installed. But doing so voids the manufacturer's warranty.
Those users who have rooted their devices and consequently lost the manufacturer's warranty, can now restore the warranty by unrooting their devices.
Galaxy S3 LTE users who wish to unroot their devices and install stock official firmware should follow our step-by-step guide.
IBTimes UK reminds its readers that it will not be held liable for any mishap. Before unrooting the device, users are also advised to verify that their devices meet following requirements.
1) Install USB Drivers for Samsung Galaxy S3 to transfer files between the Android device and the computer.
2) Enable USB Debugging Mode on the phone to connect it with the computer and use Android SDK with it. [Press Menu>> Settings>> Applications. From there navigate and click on Development option and check the USB Debugging Mode.]
3) As the tutorial might wipe all data, create a back-up. If the device has any custom recoveries such as ClockworkMod/TWRP already installed, then back up data using the recovery.
4) The phone should be rooted. Click here for step-by-step guide to root and install CWM recovery on Samsung Galaxy S3 LTE.
5) The device should be factory unlocked.
6) Verify that the battery of Galaxy S3 has at least 80% charge.
7) The phone will lose root once official firmware is installed.
8) This stock official firmware is compatible only with Samsung Galaxy S3 LTE GT-I9305. Flashing this on any incorrect variant is likely to brick the device. Verify your model number by navigating to Settings>> About phone>> Model number.
Steps to unroot Samsung Galaxy S3 LTE GT-I9305 to stock official firmware
Step-1: Download appropriate(according to region) stock official firmware for Samsung Galaxy S3 LTE to the computer
Step-2: Extract the downloaded firmware zip to get a file with .tar. md5 extension along with some other files
Step-3: Download Odin3 v1.5 which will help to install the Jelly Bean firmware on the phone. Extract the Odin zip to get Odin3 v1.85.exe and some other files
Step-4: Now place the Galaxy S3 in the Download Mode by pressing and holding Volume Down, Power and Home buttons together for about 10 seconds. A warning screen will appear, now press the Volume Up button to continue to enter into Download Mode
Step-5: Run Odin3 v1.85.exe as an Administrator
Step-6: Plug in the USB cable to the phone to connect it with the computer while the device is in the Download Mode. Wait for some time until Odin detects the device. When the device is connected successfully, the ID: COM box in Odin will turn yellow with the COM port number. Also, the successful connection will be indicated by an Added message in Odin
Note: If the Added message does not come then try another USB port, try the one located at the back side of the computer. If Odin still fails to recognise the device then re-install USB Driver
Step-7: Now select these files that are extracted from the stock firmware folder to install on the phone
a) Click the PDA button and select the .tar.md5 file
b) Click the Phone button and select the file with Modem in its name
c) Click the CSC button and select the file with CSC in its name
d) Click the PIT button and select the .pit file
Note: Ignore the last three steps (step-b, c and d) if no such files are found.
Step-8: In Odin window, ensure that Auto Reboot and F.Reset Time checkboxes are selected. But uncheck the Re-Partition option. Select it only when a .pit file is being used
Step-9: When everything is set, click the Start button in Odin. The installation should begin and will take some time to complete
Step-10: Upon completion of the installation process, a PASS message with green background will appear in the extreme left box at the top of Odin. The phone will then restart automatically. When the home screen appears on the phone's screen, unplug the USB cable from the device to disconnect it from the computer
Your Samsung Galaxy S3 LTE should be now unrooted and running on official firmware. Navigate to Settings>> About phone to verify the official software version of the device.
[Source: The Unlockr]