My father had his TV go out on him. At first it was displaying no picture, but it did have sound. I replaced the Main Vidoe board. When I hooked the Tv back up we had no sound as well as picture. I then replaced the Video/Sound board as well. Still no picture or sound. I tried the reset using the plug and power button. I used a flashlight to see if it was a backlight issue. I found it was not that either. I'm at a loss as to why it is not working. My only other guess would be the power supply board, but I found no physical damage and the fuse is intact...Please Help!!!