You reset the BIOS like this:
Disconnect all power sources (power cable, video connection, and powered speakers)
Press the power button to discharge any residual power in the system (seriously)
Remove the motherboard battery and wait 1 minute before placing back in the holder
Re-connect previously disconnected power sources
Power on (BIOS should be in default state at this point)
Your CPU lacks an integrated GPU, so you must have a dedicated GPU to boot this system. In case the above doesn't get you back to an operational state, do you have access to another GPU?