I own a Zenith Model A27B33W, which is either a 25" or 27" TV, which is connected to Cable TV. The screen recently went blank. Under similar situations in the past, I was told to press first on the clicker "Menu" then "Source - Main Source" as "Video 1" and not "Antenna". Unfortunately, this does not bring back the TV. Would you have any idea what I should do? Thanks very much, Clifford Scharff