First time on forum, I have a Syma xc5-1. Used quite a few times. Quad lifts off ground then suddenly drops and flashes. and will do the same over and over. changed batteries and switched controller with neighbor for a test, still nothing. one of the motors seems to be week when I put resistance on it with finger. any help would be most appreciate. could this be the motor not letting this thing work properly or maybe the board.... maybe its happened to someone else before. the board looks a little difficult to solder if I dont have too. Thanks in advance.