is there a sound system ?
i suspect the sound is going thru the sound system and will always be on
for the video you need to use the remote and select the video source
the remote might have buttons for TV and HDMI or video
if so press video
or hdmi until you see the picture
or press menu
choose input
scroll down the input list
hdmi
dvd
sat
etc..
I can explain it to you.
But I Can Not understand it for you !
....
Connected using T-Mobile Home internet and Visible Phone service
1997 F53 Bounder 36s