About ten years ago the District of Columbia Public Library set up a computerized catalog in its main library to replace the old file card system, and set up touch screens everywhere to enable people to access the computerized catalog from anywhere in the building. Within a very few months the system started breaking down - first one then another terminal stopped functioning, and finally the whole system just ceased to be useful. One reason was that, although the screens were meant to be touched, evidently the equipment wasn't prepared for every type of touching that happened: The micro-thin sensors ceased to function when the oil and grime of a thousand unwashed fingers had been deposited on the screen, and the impact of some people who thought they were jabbing a doorbell didn't do the machinery any good either, and some people - it's hard to say - maybe their long nails or calluses or gloves or poor circulation or just coming in from the cold or something prevented their body heat from registering on the sensors.
Something like this could have happened with the voting machines.
At this time, it seems that the machines have been used very little; the touch-screen machines have been used for one or two other elections previously, IIRC.