FWIW, all three of the defective TCON boards I bought and returned solved my minor problem completely and produced a picture along with or before exhibiting their own problems, which were completely different than mine, as well as each other. The first one was perfectly fine for about a minute after turning the TV on, after which the picture went completely nuts and stayed that way. So apparently that one was unstable once it warmed up. The next two were bad immediately upon turning the TV on. The second one produced the most incredible flashlighting I've ever seen; it had the "CORRUPTED UNIFORMITY ADJUSTMENT DATA" problem depicted in the Sony document at scribd.com I linked to above. The third one exhibited a "vertical blinds" effect; it was like some semi-transparent vertical blinds were superimposed on the picture, and they'd vary in intensity as the scene changed. At this point I gave up. Note that each time I put my board back in, my TV returned to my original problem, those 4 (ultimately 8, as 4 new ones have appeared) 3" flickering horizontal lines. So I don't think there was any problem with my technique or any other problem with my TV besides the TCON board.
My point is, if it really is just your TCON, I was 3/3 for getting a viewable picture, despite the three boards all having various defects that made them unusable and actually much worse than mine. So if you can't get a viewable picture after another board, it may be time to consider it's not just the TCON board.
I ordered from 3 different companies. Clearly, these companies are salvaging boards from broken TVs without testing them, and then they're selling them as functional. If it doesn't work, so what? I'm sure they paid pennies for the broken TVs, and their return rate can be way high while still allowing them to make huge profits given what they sell the parts for. Lots of the companies advertise with similar text, claiming that the boards were taken out of working TVs with a broken screen and fully tested. They are all lying. If you get one that works, consider yourself very lucky. And be wary of a lot of these companies; a single company can have several different web sites with different names. Be prepared to jump through hoops and even have to fight a bit for your refunds.