MBP powers on, no sleep light or display.

I was given a discarded A1260 MBP. It's not working, but I don't know the initial cause of the problem. I'm hoping to diagnose it so I can at least scavenge some working parts for a friend with an ailing one of the same model.

At first it wouldn't boot at all, and there power adapter LED was dark. I was able to get it to boot by removing the battery and power adapter, held down the power button for 10 seconds, attached the power cord while holding down for another 10 seconds.

When it does turn on, the sleep light is dark and the fans are running on full.

I did some further testing today with the same results, but now the power LED is green when plugged in.

What's the likely cause of this? Specifically, does this indicate a bad logic board? My friend's MBP was diagnosed as likely a logic board failure, so I'm hoping this one is still viable as a donor.