Last year I bought a 32" TV off ebay for something like £35. It was described as "screen flashes red/white/blue, lost the remote". I searched Google with a few keywords (including the TV's actual manufacturer, Vestel) and realised it had slipped into burn-in mode and you just need to press menu to get out of it.

Picked it up saying "um yeah, I might be able to fix it", got it home, took out the remote control for a similar Vestel set, pressed "menu", fixed!