My early 2008 macbook pro (15 inch) screen won't turn on. I think it is the SMC. Help?

I went to use my computer one day and the screen wouldn't turn on. I took it to the Peachmac store in my town (they are an apple authorized repair and retail store) and they told me it was my Nvidia video chip and that it would cost $500 to repair. I then decided it would be best to take it to an apple store, so I drove 2 hours to an apple store where they told me that it was my logic board that needed to be replaced and that it would cost $310. I decided that was too much money and I would rather just buy a new computer.

I bought a new computer, and the day it arrived, I tried resetting the SMC on my mac by taking the battery out, unconnecting the charger, and holding the power button for 8 seconds. When I tried turning the computer on again, it worked. The screen turned on and everything functioned like normal. I tried turning my mac on again the next day and the same thing happened again with the screen. It just wouldn't turn on. I once again thought an SMC reset would fix the problem, so I reset the SMC as before, but this time the computer did not turn on. I did this several times and then decided to take the ram out, air dust it, put it back in, and then reset the SMC. When I tried turning the computer on this time, it worked. I waited until the next day once more, and the computer is not turning on. Is there any way to fix this problem for good?

Any help would be appreciated, but please actually read what I have posted. Please don't just tell me to reset the SMC, because as you can see, I have done this several times.

I will keep you updated if I find a permanent fix for this problem or if someone has a solution for me that works.