Why does my Vizio TV intermittently have sound but no picture?

Why does my Vizio TV intermittently have sound but no picture?

I have a Vizio E55-E2. The screen will go off but the sound is still on. I can get the screen to come back on by holding down the mute button for 3-5 seconds and then pressing the menu button. The screen will come back on for minutes/hours and then eventually it will go off again. It is not a consistent amount of time.

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