I don't pretend to know the physics of the system but from my own experience with the SNES and NES, after they get so old touching them will set them off in the manner you are describing. I have complex maneuvers on getting games to run on both of those systems. Never had a problem with the Genesis though. With the SNES I had to put every ounce of force into shoving the cartridge into the SNES to the point that I honestly was surprised it didn't break, then slowly relieving pressure until I let it go completely. Some games were worse than others, and not all of them needed it to be done.
You know maybe it has something to do with how loosely the SNES and NES holds the cartridge. I noticed that I never had that problem with the Genesis and N64 and they both held it pretty tightly. Would explain why if you touch them they go off.
Anyways just to make sure I don't get a stupid comment telling me how off base I am, I said it earlier just like I am saying it now. These are guesses and hypotheticals based solely on my own experiences with how I got the systems to work.







