I encountered something similar years ago but it never dawned on me to think about it in your context. My problem was that I had built a three axis positioning device and six weeks after install all the drive interfaces went up in smoke. After spending all the profit I had made on the original sale, and then some, and replacing everything, I discovered the probably cause. Someone short circuited an electric arc furnace in the same building and briefly pulled one phase of the three phase supply to ground. Our diagnosis was this pushed the supply voltage for the machine I supplied from 120 to something like 200 volts for many cycles which simply cooked the logic board and turned on all the power transistors simultaneously.
So we took the replacement unit back for a short while and installed some big zeners and fuses so that if the same thing happened again we would be able to prove it had suffered a serious overvoltage.