I am half way there,
I did roll back the process:
1) change back the name servers at my domain provider (mywebhost.no)
2) then do it the right way at the domain provider
3) now pointing the domain servers of fusen.no to ns1(and 2).bdm.microsoftonline.com
now I wait for it to work properly.
to ping fusen.no (the domain I try to get into my user at thetuv.no) is still not working, and to viewdns.info show that there are still issues. I worry ..
(office365 say it must take 72h to get it working)
Still being optimistic, and I hope it will work soon and within the 72h (although the 72h are more or less there already..).
Thank you for the help. If you have other ideas I will listen carefully.