Thank you for your response Paul. Sorry not sure why I thought 2009 was the previous model. I will work through the steps in that post this weekend when I have some daylight. However, given that I hear two beeps from inside the boot when I press either the boot release button on the key fob or the button on the outside of the boot itself, this says to me that both buttons are successfully sending a signal to the bsi. So I suspect the fault is either with the wiring from the bsi to the lock, or with the lock itself. Presumably I could test this by removing the lock and doing some kind of continuity test on it? Not really sure how to do that.