It will only turn on it I hold the input and channel down buttons in at the same time while plugging it in, that's the only way it will turn on......and when it's on it shows a message in the top left of the screen.......prior to this happening the bottom left corner of the screen was shaded while the rest of the screen is perfect.....any info would be highly appreciated
potentially, you have lost a LED in the bottom corner of the screen which is causing the overall backlighting to shut down and thus stopping the set from turning on normally. The method that you are using circumvents this "temporarily" (ie. until the next power off / on). Anyways, unless you are willing to do some DIY repairs, it is unlikely that your set will be economically serviced by a repair center UNLESS it is still on warranty. The effort to repair is significant and also has the potential of causing further screen problems (cracks, etc) so most centers will not attempt.