My Cloud Mirror Gen 2 can't login after upgrade to OS5

I tried to upgrade my My Cloud Mirror Gen 2 to OS5 as recommended. The process of downloading and installing the update seems to have worked fine.

Once I login using my old password the setup wizard appears as expected. HOWEVER, after a few seconds (anywhere from 3 to 20 sec) I get a “Login timed out. Please login again.” and it kicks me back to the login screen.

I have a made multiple attempts with different browsers (Edge, Chrome, etc) but always the same result. I can never make it paste the “choose a new admin password” screen before getting the error so I can never complete the setup.

OK turns out the update failed. I unplugged the NAS, and when I replugged it I was able to reapply the update