I was watching a DVD on my macbook last night and decided to change rooms. So as I would usually do, I closed the lid of my macbook and moved. I connected the macbook to the power supply and opened it up again, it seemed to be stuck in sleep (common problem, solved usually by pressing space bar) but nothing happened.
Then the computer seemed to shut itself down, with out me touching the power button. It started back up by itself as well, or seemed to. But the screen didn't light up and the hard drive didn't spin up, just the fan powered on. I turned it off again (holding the power button down for 5 secs) and turned it back on again, same thing happened, fan would start up but no hard drive spinning up or screen lighting up. But a new thing happened, it seems now when I start it up, it will start up and stay seemingly dead for 10secs then turn its self off and then back on again to sit the same way then constantly.
I have went through the steps on apples support pages for troubleshooting a macbook that won't turn on (Troubleshooting a MacBook, MacBook Air or MacBook Pro that won't turn on) and tried resetting the PRAM and SMC but neither has worked.
I have also taken out the RAM and cleaned it of the white gunk that had started to build up on the contact points, still didn't help.
It's also not a Hard drive problem as I have taken the hard drive out and connected it to my other mac through a USB controller and backed up all my data, just in case. Although i doubt that's what causing it, if it works perfectly.
I have a gut feeling that it's the logic board that has simply stoped working, which means an expensive repair.

Does anyone have any suggestions to get my macbook working again? I'm quite frustrated
Sorry if this is long. This is my first post, and I guess it's better to be descriptive with everything.