Try re-setting the BIOS to factory defaults. This can be done by removing the RTC battery (Lithium CR 2032) on the motherboard. Leave it out for 10 to 15 minutes. Then re-insert this battery. This is worth a try. May or may not solve your problem.
Have you tried contacting the person you obtained this computer from?
Another option is to send it back to the manufacturer along with proof of ownership and have them reset it for you.