Hi again.
After finishing step 1, Windows has restarted and after booting has showed a blue screen with message "Cleaning". It has finished and I was able to enter into Windows normally.
Step 2 has finished with "100%. The operation completed correctly".
At Windows Update, clicking on "Seek updates" says "Everything is updated". The KB5030211 update has disapperared from the list of updates.
I'd like to think all is ok again.
Anyway, thanks a lot.