Service manuals usually detail exactly how a board/part is removed and installed. Not all machines have this but if you can not find where it fails due to assembly errors you may have to have the maker repair the laptop.
Unfastened the mainboard get out the laptop , it is run normally, but when inserted it into the laptop and press the power button after the flash of laptop has a little light and then it has no signal after press the button but it has no signal again. But when I unfastened the mainboard get out the laptop , the mainboard test runs normally.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic