When I first got this Mac it sometimes had a chime and came on but it would cycle to black screen and them would display login screen. I shined a light on screen sometimes it would just be backlight not coming on, but the next time it would be no display at all. I didn't do anything to it beside testing a few points. It got worse where now it doesn't chime or display at all. Board looks clean but only little spot of corosion I could see was pin 1 on U7400 and u2600. Don't usually work on mac's and not a lot of time so thought I would see what you pro's thought. Thanks