couple suggestions to try.
change graphics card, it may have failed, it looks like pc trying to post but no graphics output,
listen for beep code when turning pc on,depending on bios make different beep codes, though usually 1 long beep means no graphics output.
try to reset bios, this is controlled by a jumper that is found near battery. pin 1 2 normal 2 3 reset bios, another trick remove multipin plug from board that carries power from psu to board. then replace.
good luck.
bob macdonald, August 2007