I bought A 2015 from a used car lot, defective with the same issue, It is fixable, but the battery need to be removed to get to the BMS and current sensor. The German site EQpassion.de has also good info on the battery removal. Look at "EV battery replacement" here in the Forum there is good information in it. So far so good my Smart still drives. Bill Kichman can reprogram the BMS if it does not reset. He is in Pensylvania. I had to send my BMS to Lithuania and i also needed a current sensor from Germany. I dont know if they figured out on how to reprogram the BMS without removing it from the battery. Or having an alternative to the current sensor. Also messing with the battery is dangerous. There is no Off Switch. max 400VDC. The battery weight is about 400lbs