If you have difficulty pairing your remote, you may need to try the procedure several times for it to work.
The Pairing procedure as stated in documentation from Mini with some input by me is as follows:
The radio-control key is supplied with a permanently integrated, rechargeable battery. The rechargeable battery is charged in the vehicle via the EWS loop antenna when inserted in the ignition lock and terminal R is switched on (ignition lock in position 1 or 2).
The rechargeable battery discharges after 1 year. A fully discharged rechargeable battery must be recharged for at least 30 hours until it has regained its full capacity.
Function:
The initialization procedure allocates the key transmitter to the general module. During initialization, a code is generated in the key transmitter and then transferred to the general module. The code is stored in the key transmitter and in the general module. The general module recognizes the keys belonging to the system on the basis of this code. Only commands from these keys are then carried out.
A maximum of 4 keys can be initialized for each vehicle. The codes of all other keys are deleted when a key is re-initialized. This means that all the keys of a system must be initialized simultaneously.
Sequence of the initialization:
Carry out key transmitter initialization in the vehicle interior.
1) Unlock vehicle via central locking and close driver's and passenger's doors. (Central locking is the console switch under the radio)
2) Briefly switch on terminal R in vehicle (maximum 5 seconds) and switch off again. => The system is now ready to be initialized.
3) Press and hold ”unlock” button on the key transmitter.
4) Point key transmitter in direction of aerial (the rear view mirror, not necessary) and, with the ”unlock” button pressed, press ”lock” button three times within 10 seconds. => A new code is generated in the key.
5) Release both buttons. => The general module signals that initialization of the key was successful by locking and unlocking the central locking system.
6) Repeat the procedure as of Point 3 (= press and hold ”unlock” button on key transmitter) to initialize the other keys. Terminal R must not be varied during this procedure.
The initialization procedure is terminated if terminal R is switched on.