Read
this thread.
The two most important things are to disconnect the battery negative terminal quick release before trying to inspect the wiring, and don't open the hatch again until the wiring has been properly checked.
To inspect the wiring once the battery is isolated, open the hatch from the inside using the emergency release.
If the wiring is faulty, there is a significant risk of collateral damage to other electronic components on the car if you open the hatch with the battery connected.