No Picture but sound

Unfortunately, I can't find any service info on this TV. Does anything else happen when you hold the mute button down?

I don't know why that would cause the screen to flash on. That would say the backlight is working, though something may be affecting the backlight voltage.

It could also be an interaction with the audio on the main board.

@chrish95544 with what you are describing and it being a Vizio TV, failed backlight strips are the number one suspect. To verify this, turn the TV to a channel where you can hear the sound. Next, use a flashlight and shine the beam at an angle against the screen. Do that in a darkened room. See if you can make out shadows or shapes. If you do, then it is your backlight that has failed. It will require you to change the backlight strips.

If you do not see anything, unplug your set and remove the back cover. Then visually check the boards for any obvious damaged components. Check all the wiring and unplug the wires and plug them back in, make sure they are properly seated. Post some images of all of your boards with your question. Use this guide iFixitでの質問に画像を追加する方法 for that so we can see what you see. This could be either a power board or a T-con board issue.