Stupid Question?
Have you tried a "finger smashing" on the key a lot as soon as you push the button? Even if you still don't have picture.
Or force an error to bump up the option to enter BIOS.
Not having a keyboard plugged is one. On ASUS boards disconnecting the CPU cooler is another.
Some systems like DELL re-starting with the shift pressed will restart directly to BIOS.
Have a try.
The Englishman