This is from a post by Dave (AnubisZed)
1) In the passenger footwell, unscrew the 3 Phillips head screws and remove the kick panel.
2) Disconnect the plug coupler for the Junction box (long 47 pin plug plugged into the underside of the fusebox).
3) Find pin 12 on the plug. Using a length of wire tap this to a live fuse and you'll hear the boot unlock. You may need to do this a couple of times.
4) Reconnect the plug coupler and put everything else back as it was.
Link to post
https://z4-forum.com/forum/viewtopic.php?t=138150