You may need clear the CMOS removing the CMOS battery and all power cables from the power supply to the motherboard, leaving the system without power all night, the next day reconnect the power cables, move the BIOS jumper from pins 1 and 2 to pins 2 and 3 and power up the motherboard, the system should boot to the BIOS on maintenance mode, load defaults and save the changes, then power down the system and place back the BIOS jumper to pins 1 and 2.
If this does not help, try a BIOS recover with the information on the following site:
This can be done with no video at all, just be sure to remove all components not required for the BIOS recovery, including hard drives, optical devices, printers, card readers, keyboard or mouse. It should take up to 15 minutes to complete (even with nothing on the screen)
Also swap the memory, try using tested memory instead, the list of tested memory is posted on this site;