I had exactly the same problem on the drive with my T6.1 roof as discussed in the control panel section:
As we haven't been able to use the van since we got it in March, we thought that we would have a "night away" on the drive last night. The roof has been fine until now and raised ok yesterday. Today, I can't get it to respond when I need to lower it. The display on the new style control panel...
vwcaliforniaclub.com
I had hoped to reboot the control panel to fix the problem and could not establish how to do so. I considered doing a manual lowering procedure but found the instructions in the manual insufficiently clear. On the Monday morning, I spoke to the dealer in Preston who was actually very helpful but could find no information on how to do this on a T6.1. They got on to VW who could not help either. It appears that it is not possible to reboot the control panel in a T6.1.
Ultimately, their suggestion was to call out roadside assistance and ask them to disconnect and then reconnect all three batteries. They didn't want me to do this myself. They also said that they were glad that I hadn't decided to lower the roof manually as in their experience, doing so causes problems.
So after having tried at least 20 times over the previous 48 hours to close the roof to no avail, I called VW roadside assistance. To be fair, the guy who came out had never seen a California before, let alone a stuck roof. As I was demonstrating the problem to him, the roof sprung back to life and closed perfectly without any intervention. I cannot explain this.
I did manage to get him to do a download of the log from the OBD port which showed the following error:
B1B6EF8 Control module for special function 2 Pop-up roof tilt position (00001000 passive /sporadic)
The roof seems to have been ok since but I'm intending to get it checked before going away. Very strange.