Model # is UN50J6200
Had been powering off unexpectedly for a few weeks, now has whole screen of vertical lines. Have removed back panel and cleaned contacts with compressed air. Specifically, the power connection between boards and also the flat screen connection ribbon. None of the wiring has any apparently burned spots or corrosion. There is also a small pixelated spot at lower left of screen that appeared, screen has not been bumped or hit to make that mark appear, was not there one minute and then there the next. What do I need to replace?