What is the correct way to shut down a cluster ?

I shutdown my 4.1 cluster following this guide https://github.com/rharmonson/richtech/wiki/OSVDC-Series:-oVirt-3.6-Cluster-Shutdown-and-Startup as the NAS hosting the nfs mounts needed rebooting after updates.

( I realise the guide is for 3.6, surely not that different ? )

However hosted engine isn't starting now.

failed liveliness check

I've tried connecting from the host starting the HE vm to see what's going on with:

virsh console HostedEngine

I don't know what authentication it requires, tried engine admin details and root os...

hosted-engine --add-console-password
Enter password:
no graphics devices configured

unsurprisingly, remote-viewer vnc://localhost:5900

fails with Unable to connect to the graphic server vnc://localhost:5900

What can I do next ?