I have had this used laptop for about a month. After turning it on the other day I got no display. I tried reseating the hard drive, memory and battery. Additionally, I plugged a VGA monitor into the external adapter to determine if it was simply the internal video or not. I did not get a display on the external monitor. What are some other tests I might run to determine if I have a video problem or some basic motherboard/BIOS type issue?