Hi, I had the exact same problem. The version I have is un55tu7000fxza. When switching on from cold, a picture would either be dark, dim, or full brightness. Never knew what I was going to get. The lcd panel was fine, ie, I could see a picture if shining a flashlight into it. What I discovered is that by applying some gentle flexing to the tv, mainly towards the bottom, I could alter the brightness. Sometimes it took a fair bit of time to get the picture stable in terms of brightness. An obvious bad connection somewhere. Took the back off and gently flexed the main board with an insulated tool in various places. Wiggled the connections, especially the one that powers the backlight. All was good. Some gentle tapping on the metal backplate showed that the backlight was sensitive to this tapping. Time to take the lcd panel off. With the backlight led strips exposed, I wiggled each one of them, especially in the middle connection where two strips butts into each other. The strip closest to the bottom felt very...