There's a mechanical door handle on the interior.
If you run out of batteries completely and need to get in the procedure is:
1. Open a small panel on the front and apply 12V to the emergency cables to unlock the frunk (this only works if the car is powered off as I understand)
2. Jumpstart the car's low voltage battery, located under a panel under the frunk
3. Unlock and open the door normally
4. Attach an EVSE charger to get the HV back online as well