I am trying to diagnose a no backlight problem with this 50 " Sceptre. The red led turns blue when powered on, but no video. I don't know for sure if the audio is working because I don't know what source is selected for the tv. I shined a flashlight into the screen and do not see any video information. I have replaced the main board, but nothing changed. I have 5, 12, and 24 volts coming from the power supply. The backlight connector shows a high voltage at power on, but slowly drops to zero. I thought that since it is led backlit it should be a low voltage for that. My question is, does anyone know what the led backlight voltage should be for proper lighting, and if you have any information that would be useful here. Thanks.