I have a compaq presariocompaq presario that had a dvd that quit and i replaced the dvd drive and before i did that the computer worked fine. after i plugged the dvd drive in and put the computer back together i tuned it on and no power. so i took the new dvd out and put the old one back in thinking this was maybe the problem and put the computer together again and no luck. so now the computer does not work at all. there is a very dim flashing green light on the back of the computer so i am not sure what it could be. any suggestions??