During the BIOS update process, it is important to let the system successfully complete the BIOS update before shutting down.
Manually shutting down the computer while the BIOS is updating may cause the computer failing to power on or will boot to a black screen. If your laptop powers on (power LED indicator is on) and boots to a black screen after the BIOS update, please try the steps to see if the issue can be resolved.
If you encounter other troubles with the laptop cannot power on and shows a black screen, please refer the below FAQ.
How to solve notebook cannot power on and shows black screen: https://www.asus.com/support/FAQ/1014276/
00:20 Reset the Laptop and Resume the BIOS update
01:11 Reset the BIOS to Default Settings