Morning. Are you saying each door has a cover where you can access the key lock? I know whats wrong with ours a pin has pulled out of the plug in the A post but its now failed with door locked! Will carry on thumping door whilst continually pressing the door open button.Only the drivers door has a key barrell to lock or unlock it.
If the electric central locking fails, all four doors have the hole/cut out that you mentioned. So to lock thedoors remove the rubber plug and put the keyinto the cut out, then rotate it to a horizontal position (towards the outside of the car, each door is a mirror of the other). Thedoors can still be opened from the inside but not outside. When the door has been opened from the inside, normal operation is restored to the outside, so to lock it againyou would have to repeat the above.
If the chid lock is on and you use this method to lock the back doors, you cannot open the door from the inside, but pulling the internal lever on the inside of the child locked door restores the ability to open it from the outside (hope this makes sense but it does work).
To open the tailgate with central locking failure there is a hole on the inside, in the middle almost at floor level.