S80 Keyless Entry Failure

Sounds familiar! I had almost the same issue with my old Audi A6. Keyless stopped, errors galore. In my case, it turned out to be a broken wire inside the door where it flexes every time you open and close it. Have you checked the wiring harness that goes into the door? Especially the plug connection of the component?

Interesting! Where exactly should I be looking for this broken wire? Is it something I can easily get to, or am I better off just taking it to a shop?

On my Audi, it was inside the rubber boot that protects the wires where they go from the car body into the door. You can usually peel that back to inspect the wires. But honestly, if you're not comfortable messing with wiring, especially near the door module, you're probably better off letting a pro handle it. Those modules can be finicky. I was lucky, a friend helped me out, but it was still a pain.

Cheers for the advice! I took it to a workshop and they confirmed it was indeed a defective cable/plug connection. Cost me 95€ to get it sorted. Annoying, but at least it's fixed now!