First, please practice in manual mode. There are very few [though there are some rare exceptions] cases where if you are proficient in manual you won't be able to rescue a craft from 'a little accident' especially if you recognize the circumstances in which you are flying and think ahead about when you might not have GPS, where there might be crosswinds, etc.
Second, your Gimbal is likely toast in one way or another if you crashed with it onboard. Unmount it, unplug and replug all connectors (checking for damage or lifting solder pads as you go)and try again. If it is still erratic it is probably time for a new gimbal.
Third the motors not spinning could be caused by a number of things, nearly all of which will require some form of either minor or major surgery. You can check the following without opening anything
1. that they aren't simply jammed with debris
2. That the bell housing is still aligned with the windings and centered on the shaft
3. That the motors turn freely.
Check those things and report back. IF all those are true [and probably even if they aren't] come back and we can give further advice