Running a brushless motor unloaded will make it heat up very quickly, never give a brushless motor full throttle on a car stand/bench/etc. for more than half a second. If you got any smoke at all, it got too hot. Sometimes the rotors will detonate doing that but in your case, it sounds like you got it hot enough to start to burn some of the sator. It will probably still run, it will probably not be as fast as it was.