Perhaps that was the cause. This buggy has been put through the wringer over the last year or so though. It has seen much harder bumps than the clean landings I was hitting yesterday. The hill is 40 feet tall, but at any point the buggy was never more than 8-10 feet up from the slope. It's not like I was jumping off a cliff ;) My guess is a solder joint on a fet gave out and then touched another shorting it. the black smoke was from melting plastics. There was white electric fire smoke too but the plastics smoke was thicker.