Tesla MODEL S Operating Manual page 15

Keys and Doors
Note: Unlocking Model S using this method
disables walk away locking. You must
manually re-enable walk away locking after
replacing the key's battery.
14
Opening Interior Doors with No
Power
If Model S has no electrical power, the front
doors open as usual using the interior door
handles. To open the rear doors, fold back the
edge of the carpet below the rear seats to
expose the mechanical release cable. Pull the
mechanical release cable toward the center of
the vehicle.
Model S Owner's Manual