Has a flat battery from standing too long! on Charge.
I had a play with the tailgate a little while back and found that the boot release worked if the boot was part open. I suspected a broken wire in the look near the hinge, so today pulled out the tube, and indeed found a thick black wire in two parts!
I rigged a little wire to join them and the boot works fine, I just need to solder in a little replacement section of wire.
I strongly suspect it’s a main power feed to the boot, and as such probably supplies the demister too!