Compare to other Android devices, I think that flash ROM or firmware into Samsung Android devices is more easy and sample. Samsung Users not need unlock bootloader and without any expert command, then you can manually flash the firmware. You only need install Samsung Odin application and Samsung Driver into your computer to change the Android devices stock firmware.
But, I have mentioned before that manually flash to change the Samsung Android devices such as Galaxy Note 2 and Galaxy S3 has the risk especially the phones bricked and void the phone warranty. Bricked mean your phones firmware was crash and unable boot into Android OS. When you press the power button, the bricked phone only will display the warning “Firmware upgrade encountered as issues. Please select recovery Mode in Kies and try again” .
Don’t too worry, your Galaxy S3 still can power up. So there still has solution to enable your phone to boot into Android OS as normal. Before start discuss on how to solve the bricked phones issues, I think you need to know the reason why and how your Galaxy S3 will brick. Here is:
1. Unplug Galaxy S3 connection from computer (Odin application) during the process of flashing the firmware. You need wait until the firmware complete flash into Galaxy S3.
2. Flash wrong firmware to unsupported Galaxy s3. You need to make sure the firmware or ROM is support your Galaxy S3 Model. International Galaxy S3? AT & T Galaxy S3? T Mobile Galaxy S3?
1. Download and install Samsung Kies on your PC. Restart your PC after installation complete.
2. Download the S3 firmware (.zip) and then Extract the file (now you will get .tar file) into your PC.
3. Press your Galaxy volume Down+ Power Button + Home Button to enter Downloading Mode.
4. Open Odin (download Link) on PC, then connect your S3 to PC via USB connect USB.
5. Make sure Odin Detect your Galaxy S3.
6. Press Odin PDA, then select the downloaded firmware (.tar).
7. Now click Odin Start button to Flash the firmware into your galaxy S3.
8. That all! Your Phone will reboot once the firmware complete flash into your S3.