I had the same problem, but I figured it out for myself. So before you spend money on repairs here’s what I did.
If you tried uplugging your TV and holding the power button down for 10 - 30 seconds and plugging it back in the wall and that didnt work, try this method that I discovered on my own:
1). Hold the ON button in on your Vizio TV. Do not release it
2). Press the menu button on the remote control and select SETTINGS
3). Select RESET
4). Follow the steps to reset your TV.
This should work. Mine works just fine.