I agree, touchscreens are a bad idea. If you absolutely MUST switch to electronic voting, physical buttons are more user-friendly, and none of that "calibration" BS exists with them.
I am visualizing an improved electronic voting machine. It has a screen up top, but it is not a touchscreen, it is there merely to display information regarding the issue currently being voted on. Below the screen are four rows of four buttons per row. The first three rows of buttons would be used for the candidates, and the last row could be used to confirm the selection, clear the selection, go to the next ballot, etc. Each button is about 4 inches wide and 2 inches tall so they are large, obvious and easy to press, with a brightly-painted half-inch gap between the buttons to make the separation between the buttons stand out. Each button has its own small backlit LCD screen inside it that can dynamically change with the ballot to display various candidate names, yes or no, etc. Think similar tech to the Optimus keyboard, but with much bigger buttons and equally bigger screens inside the buttons. Whenever the voter goes to the next ballot, the displays on the buttons automatically change to the choices that apply to that particular ballot. Up to 12 candidates could fit on a 4x3 array of buttons, but in most cases there would be far fewer than 12, so I imagine the blank buttons could go completely black, to make it visually obvious that they will do nothing if pressed. If, somehow, there are more than 12 candidates, the 12th button could be used as a "more choices" selector that, when pressed, will change the candidate buttons to the next page of candidates, and it would be a different color to make it stand out so people realize there are more choices beyond the first 11 candidates.
Admittedly, there likely would be better designs that could be thought up. But, this quick off-the-top-of-my-head design still would be an improvement over touchscreens in my opinion.