If the electrical power door lock switch is not operating (e.g., dead car battery) the only way to lock the door(s) is with the mechanical key from the outside key hole.
Doors without an outside key hole can be locked as follows:

NOTICE
If the electrical power to door lock switch is not operating (e.g., dead car battery) and the liftgate is closed, you will not be able to open the liftgate until power is restored.
Rear Occupant Alert (ROA) System
The Rear Occupant Alert (ROA) is provided to help prevent exiting the vehicle with a rear passenger left in the vehicle.

You can activate or deactivate the ROA from the User Settings mode in the cluster LCD display. If your vehicle is equipped with an infotainment system, you can learn how to setup on the website via QR code in the infotainment quick reference guide.
The option can be found under the following menu:
)
several
times on the steering wheel until 'User
Settings' menu appears on the LCD.
)
and the OK button on the steering
wheel.If your vehicle is equipped with the infotainment system, the option can be found under the following menu:
WARNING
The Rear Occupant Alert (ROA) system does not actually detect objects or people in the rear seat. By using a rear door opened and closed history, the system informs the driver that there may be something in the rear seat.
CAUTION
So even if a rear door does not reopen, the ROA system alert can occur.
Storing memory positions
Driver position memory system reset
Operating door locks from inside the vehicle
Components and Components Location | Windshield Wiper-Washer Switch