OK, for starters, I have no experience fixing TVs like this, partly because it's not my line of work.
But, I am familiar enough with using them, and anything using circuit boards and whatnot, that the smallest thing can go wrong that, if you knew what it was, might be a $5 fix, but would take so long to find that the service time alone makes it too expensive. Also, the tech industry moves so fast (yay!) that parts of "outdated" TVs from 3 years ago are hard to come by (boo).
So, unless someone here has specific experience with this issue on this model, chances are you will have no choice but to donate that TV to SARCAN or something and buy a new one. The joys of "progress", right? At least the new TV will be better...
Just my non-expert opinion.