I have one of these sets that is only 6 years old. Screen is completely black when trying to watch FIOS TV but I do receive audio. I was able to rule out that there was something wrong with the cable box by swapping out a new one.

When I connected my DVD player, I get audio, by only a couple of very faint red images on the screen when playing a disc. Any thougths on what is wrong with it?

[NST]

Can you see the OSD (on-screen display) characters such as Volume, Channel, AV input etc (when you press a button on the TV's remote)? Does the fault remain when watching analogue TV via an aerial? Have you tried another AV input?

Yes, the OSD gets displayed and I tried connecting various components using different inputs. I have yet to try just an analog signal and not actually sure if I will be able to pick up a signal though.

[NST]

First, check the cables. If it's affecting all the video inputs then it's most likely the fault lies with the way the incoming AV signals are switched.
This could be something as easy to fix as a dry joint, or the replacement of the relevant IC. It's not a DIY job (unless you are suitably qualified), so you'll have to ring up a few local repair shops and get a quote.