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Either something else was damaged, in the workings, when the device was dropped and broken... or else, you have not calibrated a sensor for the range of the worm gear (and the parts that it moves). A sensor switch ought to indicate the position of the parts the worm gear drives/moves, and if it isn't indicating anything, the worm gear may be being driven endlessly in an attempt to find a return signal or indication from that sensor.
So look for a sensor switch that isn't close enough to indicate anything, and look for a disconnected cable or broken wire, or a cracked circuit board, etc.
I'm sorry to say I'm not sure.
But if there is no sensor, then the other position than the one you have tried, is the end position of the worm screw.
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