Before you go down the road of the bcu you need to pull and inspect the door lock actuator and make sure its working and that no cables or plastic bushing is worn or come drift.
Mini cooper door lock problems.
If you use a code reader that can read bmw mini specific codes it will let you know if there are any issues with the bcu.
However the driver side actuator does take a bit more time to install as it has the key lock linkage to also get back in place.
Door latch problem of the 2005 mini cooper 1.
Replacing the door lock actuator is necessary when the lock stops properly responding to lock and unlock commands from the remote or dash mounted toggle switch.
The same procedure is followed for either door.
Mini cooper owners have reported 5 problems related to door latch under the latches locks linkage category.
The most recently reported issues are listed below.