I bought a alienware sentia 244110 torn apart from ebay.I already have a 17" AW that I love,but its to heavy to carry around.So I thought I would put a smaller one together to save some $. It was missing HD,cpu,memory.I bought all new including video board and DC power jack.When I plug the power supply into lapy the green light on lapy comes on for about a second then off. When I push the power button It flashes on once then nothing.What could be the problem? Maye motherboard?