Dear all, similar issue here - but solved.
Installed PolyBruteConnect on Win10 - all fine.
Trying to login to the software - "Software not activated on this computer" - trying to login - failed
The Polybrute was DEAD - switching off, pulling the plug - nothing - only lifesign was the Polyphony LED is on.
The error message overlayed the update functions. But the "update from file" button was slightly visible and I was able to click it - update finished fine.
Obviously it started the update process but stopped as I was not logged in.
Cause was that I did not complete the registration process - somehow I missed the importance of the Software Center.