If your device is stuck on the boot screen or can't seem to start, especially after an OTA update.
It is possible some file might not be correctly installed and got corrupted.
To solve this issue you need to follow these steps described below:
Power Off your device
Disconnect your power supply.
Underneath your Device, you have an update button (Small Hole)
With the update nail provided in your package, press and hold that update button
While pressing, connect your power supply
Keep pressing the button for 10 more seconds.
After the 10 seconds, your device should enter in the recovery menu.
From the recovery menu, you need to select, Wipe Data, Factory Reset.
After this, reboot your device.
It should now be working properly.