One of the biggest issues with these old laptops, is the Ni-Cad batteries that were left for 20+ years and allowed to degrade to the point of the various chemicals and their finding their way through the wiring insulation where they could leak out on to the circuit board and damage the various parts. First, the battery terminal rots. Then the flexible cable for the LCD gets eaten away. If you're lucky, it doesn't make contact with the SMDs driver chips on the LCD. If it does, game over. Good luck fixing that. Then it's time for the electrolytic capacitors to give up their life fluids. This all leads to boards that are not worth saving but will be good for spare parts. 

I steady hand and determination can fix just about anything. I recently repaired a board that the previous owner scrubbed away the rot and several traces with a Dremel. Yikes. That was fun to repair.

The flexible connectors can be repaired but it is a major P.I.T.A. to do it.

This is using magnet wire and very careful soldering. It's very easy to melt the substrate and ruin it. while it looks pretty, it wasn't feasible, as it wasn't flexible enough.

Below, I went with ribbon cable for this repair.