Hi, all. I am a new comer with Phantom 2 gopro4 on. When I was flying my P2 today under a bridge, the battery signal changed under 25%, and It suddenly flying high. I tired going down P2 RC for landing, but it keep just going high. and hit the top of bridge. Before this, I tried to test CL and HL mode. Is there any solution, when It is out of control some like this? as a result, my prop guard and propellers totally broken, but body is good to go. I want to know why it is happened to P2 Thank you.