i looked at mine and it doesn’t look user serviceable unless maybe you’re a body shop.
I am not wrong, as I have had to use in many times most recently when rear passenger door lock failed with door open. you would enter vehicle from cover on driver's door handle but to lock vehicle doors once they are open you would need to use this port.Ehm, sorry, but i think your wrong.
That "lock" what I mean is on the inside of the door and isn't visible /reachable from the outside. So it can't be an emergency lock when the battery is dead.
If there weren't a lock symbol on the cover i would think it's a normal screw hole cover. But the locks symbol with the "I" looks like this hole is something Special.
you just lightly push and twist to remove thin plastic cover insert your blade key to lock door then close door and it will remain lockedThe gray rectangular hole, can it be moved down with a screwdriver blade? The other possibility is that the cover when in place can be moved either up or down. Let us know.