Sorry, don't have time to read the whole thread so this may have been mentioned:
The static isn't killing the buttons, it's probably damaging the inputs to a microcontroller that monitors the line.
It surprises me that the button inputs don't have some sort of ESD protection.
It's probably difficult to modify the circuit board, but typical methods of dealing with ESD are diodes, high voltage ceramic capacitors, and spark gaps. You could tie a 1000V ceramic capacitor (around 22pF) across the switch terminals to ground. (If one side of the switch was a ground, you could just go right across the switch.) Unfortunately, implementing diode clamping or a spark gap (more effective methods of ESD protection) really depends on how the circuit was designed. (I suppose you could build a crude spark gap by grounding a solid wire on one side and running it near the switch itself in a loop. The trick here is to try to put a grounded wire in a location where a spark will jump to it instead of to a switch lead.)
