Finally, Samsung has official releases the latest Android firmware, Android 4.1.2 for Galaxy S3 GTi9300. This firmware modem version is I9300XXELKC and CSC is I9300OXXELK4. You can update your Galaxy S3 GTi9300via Samsung Kies software (How To) or OTA update. If Android 4.1.2 still not available or reach on your region, then you still can manually flash Android 4.1.2 firmware into your Galaxy S3 via Odin application. But, please note that manually flash any firmware into your Galaxy S3 will increase the binary counter and void the phones warranty. Before start, you can refer here – Galaxy s3 Hints and Tips. The Android 4.1.2 firmware bring lot of new features for Galaxy S3, you can refer here to get more info.
As I have mentioned before, as Android application developer, I will update almost all leaked or latest official firmware run on my Galaxy S3. It is important for me or others developer to run test application on the latest firmware. Here is the step by step tutorial share with you how to manually flash Android 4.1.2 I9300XXELKC firmware into Galaxy S3 GTi9300:
Step 1. You need Samsung Diver to enable your PC able detect and connect to your Galaxy S3. So you can Download Samsung Galaxy Driver (Link) or Download and install Samsung Kies on your PC. Restart your PC after installation complete.
Step 2. Download (Link ) the S3 firmware (GT-I9300_XEO_I9300XXELKC_I9300OXXELK4_I9300XXELKC.zip) and then Extract the file and now you will get ( GT-I9300_XEO_I9300XXELKC_I9300OXXELK4_I9300XXELKC.tar file).
Step 3. Go Setting >Developers option to enable USB Debugging on your Galaxy S3 and then Power off your Galaxy S3.
Step 4. Press your Galaxy volume Down+ Power Button + Home Button to enter Downloading Mode.
Step 5. Open Odin (download Link) on PC, then connect your S3 to PC via USB connect USB.
Step 6. Make sure Odin Detect your Galaxy S3 (How to know).
Step 7. Press Odin PDA, then select the downloaded firmware (GT-(I9300_XEO_I9300XXELKC_I9300OXXELK4_I9300XXELKC.tar).
Step 8. Now click Odin Start button to Flash the firmware into your galaxy S3. Don’t unplug Galaxy S3 connection from computer during the process flashing Android 4.1.2 firmware.
Step 9. That all! Your Phone will reboot once the firmware complete flash into your S3.
That’s all Enjoys!