Why would you need the back door to open if you can live without the window going down?
The window needs to go down for the door to open - so the 2 do not compute.
There-in lies the problem with your door not opening... it needs the window to drop before the CCU will power the opening actuator.
So your first job is to fix the back window issue. It may be damaged wiring, eg where the loom swings on the door hinge side, it could be the relays for the window (which is behind the plastic trim in the boot area) and highly likely in the regulator wiring.
If it was me, I'd replace the regulator, but it could be a complete waste of cash. Dunno if you could remove the (wiring) contacts off the regulator motor and plug something else in to then that will not blow fuses and press the window button to see if it stops it. I dunno how the CCU will respond to that because of the sensors if gets a feed from on the regulator. The relay is a double action relay (for up and down), still shouldn't be too expensive as a replacement to see if that's the issue.
The Rave workshop manual has full wiring diagrams so you can see what is in the window circuit, and pics of all the connectors so you can see where they are. Its a great resource...
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