Before any trip to the dealer do your very best to work things out by yourself. It's very common for your dealer to take your RV in for service and not work on it for months. And even then not be capable of fixing the problem.
That radio I assume is the Connexx WMSDVDZ3. It is sold to OEM manufacturers from Riverpark in Illinois. They have good telephone tech support. So, yes, call them first.
Here's a link to the radio's webpage at Riverpark. It might also provide enough info to help you. If not, call them (800) 442-7717 · (574) 522-7781.