I have a Dell Latitude D800. I just changed the system board but the system won't boot. When I plug the ac adapter into the system I see the battery charging LED come on and stay on continuously while charging. However when I hit the power button all of the led indicators come on and shine green for about two to three seconds and then the system just cuts off. I never see a Dell splash screen. No Bios screen. No flashing cursor. Any ideas where I could start with this? Any and all help is appreciated because I really need this laptop working.