Newbie here. We have a jjrc h8d and I was replacing a motor but whenever I connect a new motor it starts spinning with the battery hooked up and power off. The other 3 motors do not spin. So if I don't have the handset on and the quad is powered down that one specific motor will automatically spin as if it was being throttled. It's only that specific one and I've tried 3 new motors. Same result. Any ideas?