The time it takes for an OTA update to complete depends on the size of the update. It is best to run the update when you have good signal strength.
1. Run the update
2. The phone will restart and the screen will only display a window for some time.
If there is no change on the screen for several minutes:
3. Press the volume-up and power keys together and hold for 10 seconds - this will force the phone to restart.
4. When the phone has rebooted, head to Settings > About phone > Software Update and try to install the update again
Please contact customer service if the problem persists.