Seeking to monitor VGA/HDMI Off/On state

I monitor about 200 Windows-based endpoints that display advertisements on LCD screens. Some TVs have unusual behavior when the power flickers, and although the PC connected to the LCD screens works fine through these power issues, sometimes the LCD screens don’t come back on and there’s no way that I know of that can monitor that particular metric.

This metric is critical because when a screen is down a customer will get upset (naturally) that their advertisement isn’t being displayed.

The different PCs used to display advertisements are various brands, as are the TVs so there’s no real consistency between them.

Anyone have any ideas how I can get this metric into Grafana to be monitored & alerted?