I was working on a project which had a DC-DC boost converter (7.2V input, 24V output) running a A4988 stepper board. I managed to get it running, however, on my last test run, the A4988 failed. Also, when it failed, it shorted itself ENTIRELY, putting 24V into my Pi and destroying that too!
Has anybody else experienced anything similar? I had all the recommended precautions in place: a 25V, 100uF cap across the inputs 0.5cm away, the motor was plugged into the board, and the driver failed right in the middle of my program, when the stepper was already spinning at 50revs/sec.