DeConz wont start

My ConBee II was working great but then I connected via a USB extension lead and it stopped.
Now it’s back exactly as it was, plugged into the USB port (the same one) but it will not start.
I have tried restarting HA and rebooting the computer but no joy.
Log shows “Config entry for deconz not ready yet. Retrying in 5 seconds.”
It is still showing up in the hardware page and the same address is still in the config:
I’ve tried it with /dev/ttyACM0 but no joy either
What might have happened and what can I try next?