Heat is indeed a major enemy of electronics, so that's a good bet. Maybe you could add some vent holes and maybe a small "muffin fan" to help circulate air. Any of the zillion computer fans would work if you have 12v nearby, but there are 120v modes too.
Sadly, finding someone to fox a tv these days is near impossible, plus it would probably cost as much as a new tv anyway.
Former owner of 2004 American Tradition and several other RVs
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC