There was a good bit of corrosion on the little ribbon connectors that connect each side of the display PCB. I suspect that may have been the issue on mine, so I would give that area special attention, along with the legs on ICs.
Ok just gave it a REALLY good clean, still doing the power cycling thing. Not sure what else to try except maybe a new screen, which i don't think ill be able to get unless I find another 140. I'm still open to ideas though!
Ah that's frustrating. Well, you know the symptom happens when the display is connected, and you've determined it's not the cable. So the issue is either on the display board still or on the interconnect board. Close visual inspections of both, the connectors, along with a multimeter to check for shorts or anything amiss would be my next step.