I have an old MacBook Pro (late 2006) and he won't boot anymore. He fell down the table and ever since, he's not working anymore. When I try to boot him, the hard drive and the fans starts spinning, but after a few seconds everything is shut down with a "loud" click.

Here is what I've tried:

 - Reinsert the Ram
 - Replacing the RAM with new ones
 - Used the RAM in another Mac, works just fine
 - Unchained the hard drive and used an other one
 - Used the hard drive in another Mac and PC, works just fine
 - Resetting everything you can (PRAM, SMC,...)

Calling Apple Support won't do much since the warranty has expired like 4 years ago. 

What I'm afraid of, is a broken motherboard or graphic card (which I don't know how to test this). What are you thinking of when you read this story and what do you think I can do about it?