This is a Feigao IPS 12mm replacement?

These motors have a 'weak spot'... where the wires enter the can (on the 'back plate') they can get damaged. If this happens they short to the can or each other / something and you get the behaviour that you describe (stuttering when trying to start)... on the CC10 you may see the 'full throttle' light is on all of the time or it is flashing. The can of the Feigao will get warm / hot even though it's not running.

I busted two of these motors in crashes before I decided to stick with cheap brushed IPS units that are more robust. I really liked them but I still crash too much trying stuff or 'hot rodding' to tolerate the lack of robustness of the wiring (or maybe they cannot tolerate me ).

If it's new (and my diagnosis is correct) then return it....