|You say you tried F2 and F12. Does that mean those options showed on the screen but pressing them left you at a blank screen or did nothing ever show on the screen and you just pressed those keys because they're the ones to use to access the bios and boot order?|
As already mentioned it sounds like a hardware problem either with the computer or the video connection. Did you verify this 'new' computer worked before bringing it home? Did it then have a different video connection than what you're using now?