Probably a bad capacitor on the PCB or bad power regulator. If you are inclined, unplug it for a couple of days. Let the power drain, then open it up. It it's a bad capacitor you'll notice it. I've replaced bad capacitors on other branded flat screens before and its not that hard. There are a lot of Youtube Videos. Just don't crack it open without letting it drain for a couple of days. Otherwise you hit the wrong capacitor with a charge and your heart will explode.