I’m in exactly the same place now… norns fell off my wifi at the
Setting up network-manager (1.6.2-3+deb9u2) ...
point, and now I daren’t reboot it because the update is still running.
How long were you and Boris outside for? 
How did you know the update was complete? Does the version change to 190314 on the SELECT / SYSTEM / SLEEP screen despite not being restarted, or did you just restarting?