This situation is generally presumed to be a problem with the signal source input. One is to check whether there is a problem with the connection between the cable and the TV, and try reconnecting; the other is to check whether there is a problem with the signal source switching of the TV. You can press the TV/AV button on the TV remote control to switch until the TV shows the TV signal. If there is no set-top box, you generally need to switch to TV or TV mode, and then automatically search for channels to watch.