Flashing guide:
1. Download and extract a zip file containing your desired firmware.
2. Open Odin Tool.
3. Boot your device in the "Download Mode":
Press Volume Down, Power and Home buttons at same time for 5-8 seconds until download mode is active.
FIRMWARE LINK: https://samsung-firmware.org/download/Galaxy__S__3__LTE__/91s0/OPT/I9305XXUFOB2/I9305OPTFOB2/
1. Download and extract a zip file containing your desired firmware.
2. Open Odin Tool.
3. Boot your device in the "Download Mode":
Press Volume Down, Power and Home buttons at same time for 5-8 seconds until download mode is active.
FIRMWARE LINK: https://samsung-firmware.org/download/Galaxy__S__3__LTE__/91s0/OPT/I9305XXUFOB2/I9305OPTFOB2/