Optimus 120-2154 - Manual (Page 12)

Note: The keys are labeled to show their top edges.
5. Remove the keys from the slots.
6. Disconnect the wire harness and the antenna.
7. If you are mailing or shipping the stereo, use a Phillips screwdriver
to reinstall the shipping screw in the top of the stereo.
8. Reconnect the cable to the vehicle battery's negative (-) terminal.