WARNING: Before perform firmware update, always perform phone backup! The author will NOT be held responsibility under any circumstances.
1. Settings > Software update > Download and install > Download
2. Downloading update...
3. Install now
4. Android system update > Reboot > Update (%) > Reboot
5. Phone is updating... Optimising app x of y > Optimising storage
6. Login to the phone > Finishing system update...
7. Software update > OK
