Actually, I am not one hundred percent certain why it failed. It was working, and then it just quit producing a picture. It wood turn on, stay on, everything would seem to work find, but no picture or sound.
I finally broke down and took it apart, and I found two things which may or may not be the cause. The LCD in that model a sort of pressure fit, no clips or anything hold the panel in place. The weight of the panel caused it to sort of sag, so that it was slightly curved when I pulled it out.
The other thing was that I did find some discoloration on the video board. Not sure if it is from heat, or simple failure. Or if it is just something that this model does as it ages (it was about 4 years old).
But, whatever it was, it is apparently a know issue, because I downloaded several service manuals for RCA flat panels trying to diagnose it, and they all said "Do not operate or store television in a non-upright position."
I don't THINK it was heat, though. We had a stand for it, so it wasn't laying flat on the table. But, then again, we didn't add any fans either, so that might have been it. I finally said bugger it, put it back together, and put it in storage.