Alright then. So, nothing when power is pressed? Disconnect all non-essential parts. If any keys are stuck on on the keyboard it won't start for whatever reason. If it has a hard drive then you can use that as a test to see if it starts with the top case off I'd assume. I don't think there are schematics for the motherboard unfortunately, but you can test to see if any tantalum/ceramic caps have shorted.