My H3D11-50 back lost power, and I was unable to get it to work again for a few hours, until I saw some mention of somewhat similar problems here, which were recovered by removing and replacing the back.
At the time it occurred I had the camera attached to a (relatively cheap) equatorial mount for astronomy, it was tethered to a laptop, and I was fiddling with the firewire connection to the camera. I feared it might have got a stray spike from the stepper motor, or static or something.
Are backs electrically robust, in common situations, or do I have to beware of other things than just old style flashguns?