I'm fairly a newbie to the 250 Racing drone scene (but an electronics tech, so helps with assembly/ repairs). Gonna just use for personal sport flying. Anyways, purchased it from GearBest. Out of the box, one of the filter caps for one motor was damaged/ no big deal. Replaced it. I flew it 3 times, trying to get hovering down. Last flight, took a hard landing and flipped over on grass. I locked the motors immediately after. When I flipped it back over to fly again, the rear left motor stopped turning. I measured the voltage to the motor while the other motors were on and got 12Vdc to the ESC, but no output voltage to the motor. I put 12Vdc from a test power supply to the motor directly and it twitches on each pair of its wires. I replaced the ESC with a 20A Eachine one one - same result (makes noise so I know it is getting input voltage). I tested the continuity to each contacts of the FC connector on the PDB to each motor contacts and ALL were OK. Anyone know what the problem might be caused by? Thanks in advance.