Just installed the p850c with bbshd. Charged the battery, turns on, runs great. Programmed with app to change peddle assist levels, all goes well until I turn back on where it says hello and immediately shuts off. It will not turn on again until I shut the battery off and try again. Same thing, shuts off and have to repeat process several times and disconnect battery and try a few more times then it will work just fine. What gives?