Tried to remove an old SD card and format a new one. Now I'm trying to reinstall everything via the new MyDrive Connect. The Windows 10 install was very, very fast. It's been a while since I said: well perhaps this Windows is ok-ish.
After the first install I got an error. No map installed. Then I tried to install a map .. lo and behold:
It actually worked!
Tomtom is up and running again - after at least 15 hours of trial and error that is.
I guess that the problem with Tomtom is totally uncomprehensible error feedback to the user. Figuring what's wrong takes a full blown clairvoyant or a reliable set of Tarot cards. "Install failed" does not say why.
And I still miss a Linux GUI ...