If it's the micro switch on the door mechanism playing up then the door panel has to come off on the driver's side.
If the boot mechanism has failed the all the boot trim has to come off
My dealer had to strip all of mine off as they could not originally find the fault & was trying to trace a wiring loom fault!?!?!
They could not fix the water leak as the seals on the rear window were sound. I fixed it my self by sealing the top of the interior top plastic moulding with black silicone sealant!!!!!!
The water runs into the trim when you open the boot & then when you close it it runs down the inside of the window. Justwhat you need if your rear demister is on!!!!!!!!!
I've got rid of the car now. PHEW!!!!!! I couldn't even think of what the repair bills would have been when the car was out of warranty!!!!!!!!!
Good luck!!!!!!!!!!!!