Doing a little thinking of what I might do in this case and perhaps some small bits of info that mya help---if you choose to chase it now or if it comes back later, as intermitant things tend to do?
I've not looked behind a montiro panel in so long, much of my experience may be totally out!
But when you took the panel off to get tot eh ohone cord, did it also have a group of small wires, perhaps solidly soldered to the board? I'm thinking this iwll be a place where Winnebagod adds wires to do tyhe various function and brings those wires to a poin near the panel and then those two groups of wires are plugged together. Maybe something like a Molex plug if you know those?
A couple thoughts for you to consider, if you so choose!
Perhaps pulling that board out and maybe you can pull the wires out enough to find a set of plugs and make sure they are solidly snapped together?
Not unusual for plugs like this to get snapped together near enough to work but whatever form of clamp/grip doesn't really get all the way snapped on as good as it should and they can worm around and work or not work just kind of random as the feel!
A second part of that while you have it out, is to consider looking at the wires that Winebago have installed for the ID stamped on the ends of each wire?
IF (big IF!) you find my guess right, you may be able to find the wire ID that tells you what each wire does and where it comfes from and goes to!
Then we have a list of wire ID here:
https://www.winnebago.com/Files/File...ical_guide.pdf
We can look up the ID found on a wire or work it in reverse if we know only that we want wires going to the monitor.
By getting the ID chart up, hitting "ctrl and F at the same time, we get a dropdown where we can input a term like "monitor" and get a list of where that term appears.
In this case I see a bunch to scroll through but many can be ignored quickly as they are camera or other monitors which we don't care about!
Click this snip to get a better view of what you might find.
This list will give the ID, wire size and color and then from and to locations. That info can help to locate where the other end of a wire next shows up!
Lots of hit and miss but if it comes back or you want to do some checking when not in crisis mode, perhaps a way to move?
Maybe a job for three months from now when you are getting bored?