Yesterday, we had a new HB 1000S installed. It worked beautifully. While I was out, a friend managed to find the old Sky remote where we had hidden it, and tried to use that. Disaster. Now we have only a snowstorm on the monitor.
Thank you, while I was waiting for a reply our helpful engineer rang me and told me how to revive the AV-setting on the monitor. All is now well, and thanks again.