Ursprünglicher Beitrag von: Rany ,
There is a cable that links the board to the track-pad. Remove it from both sides and examine the tips (specially the tip that goes into the track-pad) under 10x-20x magnification. If the cable is damaged/corroded (the golden prongs are corroded, missing) then you'll need to replace the cable. I had a case where the gold plating migrated from one prong to the other and shorted the cable. In which case you can use a fine needle to scratch the short. Also make sure the connector on the trackpad (where this cable tip connects) is intact. And/or clean it with a soft toothbrush dipped in 90%+ isopropyl alcohol. Let me know if any of the above helps.