W10 update March 2021 - error if updated in virtual machine

Parallels Desktop 16.1.3 for Mac

W10 March 2021 update:
https://support.microsoft.com/en-us...-of-band-ebbe0617-3a63-467a-aaaa-2a4c68a6de33

I'm using bootcamp to run W10 as well as in virtual. While i had W10 running in Paralleles, i saw a pop up describing something like "W10 needs to update and this cannot be done in a virtual environment. You need to restart in bootcamp to install this update"
At that time i was too busy and later on forgot about it. Wanted to shut down the W10 (running virtually) and the shut down button only had the option "shutdown and install updates" - so i did, since there's no choice to 'not' install the update.
After that it cannot start W10 anymore, not in Parallels virtual, neither in bootcamp.

When it starts there's briefly a W10 logo for about less than a second and it reboots the Mac again. Same in Virtual environment, there's a W10 logo blinking > endless loop. In Parallels, you cannot shut down (or quit) the W10 VM anymore, you'll have to restart the Mac completely.

Tried to fix by creating a W10 USB boot disk and choose repair Windows, but it seems it cannot be repaired this way.
Tried to use bootcamp assistant => this wizard directly gives me only one option: remove the partition of W10 where i'll loose all my data.

To make sure, i made a copy of the contents of the boocamp partition on an external SSD. I guesss the onlny solution will be to completely re-install W10?
Any other ideas are welcome
Pascal