Procedure to Update Galaxy S3 with Thunderbolt Custom ROM Firmware:
- Download the Thunderbolt Custom ROM Firmware from here to your computer. Once downloaded, connect your device to the computer with the help of original USB cable and place the zip file in your device.
- Once the zip file is placed, disconnect the device and turn off your Galaxy S3 smartphone so that it can be entered in the recovery mode. You can either enter your device in the recovery mode with the help of ROM Manager app or with the manual method which is mentioned below.
- Recovery mode in Galaxy S3 GT I9300 can be entered by holding the Volume Up button + the Home key button (the middle button). While holding these both buttons, turn ON your device. Now, in the recovery mode you will have to select “Wipe data/factory reset” & “Wipe Cache partition” so that all the data can be cleared in the device.
- Now select “install zip from SD Card” in the recovery mode to choose the zip file which you have placed in your device. Once the zip file is selected, it will take around 4 -5 minutes for applying the update. Once the device is updated with the firmware, head over to the path “Settings > About Phone” where the firmware version will be mentioned as Thunderbolt Jellybean 4.2.1 firmware.
Note: Just in a rare case if the device doesn’t boot up or show the home screen then remove the battery and reinsert the same to boot the device again in the normal mode.
Do let us know in the comments section below just in case if you face any issues as we will be more than happy to help you out. Congratulations, you have now successfully applied the update of Thunderbolt Jellybean 4.2.1 firmware in your Galaxy S3 smartphone.