Problem with diagnosing Grand California 600

[Dominika]

Hello!
We have a 2021 Grand California 600, the camper is out of warranty. It has been in the VW service for over 3 months without a diagnosis. After heavy rains and starting, a lot of errors popped up and it stopped driving. There were a few more attempts and after a few km it stopped driving again, until it finally stopped starting. The controllers were checked - in another Grand California they work - in ours they don't. The service checked the harnesses, but so far they haven't found any faults. Errors keep popping up - e.g. . indicates a sensor that needs to be replaced, but it works correctly and we are still reading a permanent error Code/version of controllers in the drive wiring harness (permanent error). The service is out of ideas, they consulted with the manufacturer and nothing came of it. Marten interference was ruled out. There was also suspicion of attempted theft. We noticed that water was leaking under the hood and that the windshield was also leaking. Maybe you have some ideas what else to check, because we are devastated...