Yep. This. If you're comfortable pulling the 5101 RAM out of its socket, often-enough you'll see some corrosion when looking into where the chip's pins would push into the socket. Or maybe some corrosion on the bottom legs of the 5101. Usually when the corrosion wicks up to the 5101 via the trace from the ground-plain running around the outside of the board, that means the corrosion's underneath the socket as well. There are thin traces running between pads on the 5101 that can get eaten away. Sometimes I'll check to see if lightly pushing down on the 5101 will help get some more flashes.

But yeah, that board.. even if you get it booting.. isn't going to be reliable for long until that corrosion is cleaned up. It's not looking like it'd take too much to clean up the board, but just depends if you're comfortable tackling it yourself or would rather just buy a replacement and save the time. Someone would still buy the board on eBay for $30-40 most likely so keep that in mind.