I read your post you sound like you know a lot more then me if build an electric car. I am no expert on electric but when l hook up the zappi scanner to the controller on a lift truck and said driver shorted l would think that there is a shorted driver inside the controller. I WOULD SEND IT out to have it looked at. Also if it was driving and that happened l would look at the a.c. motor and cables and make sure there is no short in motor or to frame. Hope l was of help