Dolphin diagnotic pool cleaner just stopped working.Son took it out of water and wrapped cord up and almost pulled wires out of plug that goes into the motor mount.

The wires in the pool cleaner probably did disconnect from the motor. You might not be able to see the disconnection, but i would guess this is the problem since you already know your son made the mistake. You are probably going to have to take it to a service center so an electrician can reconnect your wires.