By "Dead HP" what do you mean? You hit the power button and it does nothing? Does it turn on and run? I need a bit more information to figure out what the problem at hand is.
Well, my first guess would be that your motherboard is shorted out. It could be a bad switch too. Are you sure the board does nothing when you hit the power button? Do any fans turn on or anything? Sometimes a shorted out video card/dead can cause the symptoms you're having. Even dead ram, there's lots of reasons it could be doing what it's doing.
The switch would make perfect sense except how common is it that a switch fails? There are definitely no fans and the disc drives are not turning. When I get back to this little project I will r&r the RAM chip set. If nothing I will then try removing the video card. Am I correct in thinking this might at least change something? I understand that if the RAM is completely toast it won't but hopefully thi sis worth a try?!?!?!?
It's all worth a try. I go through the process of elimination. I start by going with the easiest fix first. If the switch doesn't seem like it's working pull the cable header off the board and get yourself a paperclip or something that will conduct electricity and jump the pins to turn on the system. If that doesn't work I'd try changing out the ram if you some extra laying around. After that I'd try the video card. You would think that if the video card was dead that the CPU fan would still run but I've had them short and nothing worked at all.