Boot up problem

[Gamegod322]

So I recently bought a Mac book pro from an Old friend. It turns on but won't boot up and the screen remains blank. The computer itself turns on but nothing more. Any suggestions are appreciated.

 

[Kaveman]

Plug in an external monitor and see if the problem is just the screen.

 

[Gamegod322]

So I tried the external monitor and the Mac won't even turn on now. Help please?

 

[Gamegod322]

Also, I have no history of the health of this computer. All I know is that it used to work perfectly fine but my friend left it plugged in over night one night and the next day it didn't work.