When I took delivery of my Challenger I did not have a DVD so I did not check the AV connections. When I got the coach home I found that Thor had wired the HDMI cable from the DVD to the output side of the with box and had the TVs wired to the input side. Took me about 15 minutes to reconnect the cables and all works well.
In my coach cable is run form the exterior box trough a splitter to the TVs. When connected to cable I then have to do a channel search using the menu on each television. Also for cable make sure the antenna booster is turned off. My booster is located in the same area as the HDMI switch.
Hope this helps somewhat.
US Army (Ret)
2020 Entegra Accolade 37TS
2019 Jeep Grand Cherokee Trailhawk (Toad)
FMCA - F432054