If the remote was tested or perhaps another remote tried on the tv then it is very much possible that the tv`s IR sensor (remote sensor) is defective and that is a common problem with those vizio`s.
This remote sensor is not expensive and you can buy it at the link below for $10 , just click on it;
If you or a friend is handy with a screwdriver then once the back cover is removed this is very easy to replace , it sits just behind the sensor window and has to screws and a plug to pull out and you`re done.
If that is not your cup of tea so to speak then a shop should not charge above $80 to repair this if you take the tv there yourself
If you need to find repair shops near you then look at the link below and enter your zip code ;
This will give you a list of NESDA member repair shops in your area.
This list may be limited though and you may find more by simply using the yellow pages or simply google "tv repairs" and the name of your town .
You could give a call to different shops in your area to get an idea of their rates , it pays to shop around.
If you want to test your remote first you will need a camera something like a cell phone camera , a tablet a digital camera etc. , any camera that has a display or screen to test the remote ?
Turn on the camera and point the front of the remote at the camera lens ,then while looking at the remote through the screen press buttons on the remote.
If the remote is working, you should see light coming out the front of it while looking at it through the camera screen.
If you see nothing coming out and are not sure if you did the test correctly then try it with a known working remote.
Let me know if you have other questions and if not then please do not forget to rate by clicking on the star icons at the top, then click on Submit so i get paid for my time helping you .
Also note that it will not close this post , you can come back here at any time if you need further info or help .