Without visible screen, it will be challenging to update BIOS.
BIOS update may not reset BIOS settings. It depends on what and how update is applied by the vendor.
Is the keyboard working? Do you see any LEDs for Num or Caps lock etc
What if you project the output to an external monitor using whatever HDMI port you have?
It could be that the build-in monitor is broken but display capabilities are intact?
If nothing works take it to service center if there’s one in your city/area.