Try this, copied and pasted from a mini forum.
If you have already done this apologies but it is best to go back to basics. So press the obc button on the indicator stalk until SET/INFO comes up. Then press and hold the button until the display changes. Now press the button repeatedly until the key with a tick symbol appears. Hold the button until the display changes. Then press the button to select unlocking or locking (open lock and closed locked symbols respectively) Hold the button until the display changes. You now will see the current setting. If it says off then great that is all it is. You can then select lights, acoustic signal or both. Don't forget to hold the button in when you have selected your choice then the choice is stored. Repeat to set both unlock and lock.