[RXeckless]

This worked for me
You need to reset your BMW key. Press and hold the "Unlock" button on your key. Press the "Lock" button on the key three times. Your key is now reset and should function properly.

or try, I personally did not try this method.
BMW Key Resync Method 2
Insert the key into the ignition and turn it to position I. Then turn the key to position 0 and back to 1. ...
Remove the key from the ignition.
Press and hold the unlock button.
While holding the unlock button press the lock button three times.