Any hope for this laptop?

I have a Gateway NV5207u laptop that I purchased a few years ago for college. Had no issues with it till this past spring. It started overheating and shutting off. Then one day I shut it off and it wouldn't turn back on. It eventually would turn back on. And I could use it but if I let it sit for few hours or if the battery died, it wouldn't come back on for days. I know it wasn't the hard drive. I took that out and used as an external drive (to get my school papers and such). I chucked it in its bag and forgot about it till recently. It turns on, I can hear the fans spinning, then it just hangs, but the power light is still on. My theories are A) The power button and accompanying cord have failed. B) The DC jack has crapped out C)Both or D) Motherboard fried.
Its not the power cord. I have the original, a spare from Gateway and a friend with the same laptop charger, and all three cords work on both mine and her laptops.

Any ideas? Should I shell out the cash to try both the power button and replacement DC jack or should I just junk it?

 

If it started overheating and shuting off and didn't do it before it's probably clogged with dust and needs a good strip down and clean out.

 

Its been stripped down and cleaned. I've taken the whole thing apart, reseated the RAM, put new thermal crap on the processor, cleaned and dusted the whole works. And still nothing. That's why I'm thinking its something with the power? I'm stumped.

 

it could be fractured solder joints, maybe the GPU or CPU socket needs a reflow.

 

When I gave everything a look over the solder looked okay. It gets power. The power light comes on, and the battery charging light. Just when you press the power button, the fan starts, and it hangs. I'd like to fix that laptop just because I hate dragging my new one around places.

 

I hate to say it, but repairing circuitry level errors on any computing device can be a real pain. I can only suggest junking it at this point. Sorry!