Are you trying to get into BIOS, and also having problems with your display? I'm confused
Usually to get into the BIOS when you power up, it's commonly either F1, F2 or DEL key. Sometimes it can be other F keys but usually there's a notification somewhere on screen when booting to tell you.
So, are you having problems with your display? Do you have a signal when the PC boots up, but shows no signal when you boot into the OS?