Hassio install dead - get http://hassio/hassos/info: dial tcp connection refused

Running hass.io on a raspberry pi3.

Installation has been working just fine for months.

I installed the zigbee2mqtt addon and configured it. Added some zigbee devices and it was all working.
About 30 minutes after, I couldn’t connect to Home Assistant. I try to ssh in as usual using ssh [email protected] and I get ‘connection refused’.
I could ping the IP address so the network connection is up.
I ended up removing the power and connecting a monitor and powering it back up to see if it would start.
I can see it going through the linux boot process and I get a login.
I login directly on the raspberry pi using ‘root’ and no password as per this page https://www.home-assistant.io/hassio/commandline/

If I try any command I get the error:

Get http://hassio/hassios/info: dial tcp 192.168.1.100:80: connect: connection refused

I’m using a physical network connection. I can ping the IP from another computer so the network connection is working.

I’m looking to either fix this or to get at the backups from the SD card. Does anyone know how I can get this working?