I have a 60 inch Magnavox model #60P8241. I turned my tv on today and the power came on, but there was no picture or sound. You could not even see the channel numbers or volume numbers. I have unplugged it for about an hour and plugged it back in, but no change. Still no picture or sound, but the power light is on and you can actually here it cut on, but just a black screen. Does anyone know what I should do before I make a service call?