Apple TV Crackles and Flickers

I have an Apple TV...3rd gen I believe. It was given to me for Christmas 2016. Upon opening the box, and connecting, the unit was unwatchable out of the box. The screen flickers and the sound crackles. Tried numerous HDMI cables and also cleaned all of the HDMI ports. The unit still has the same problem.

I took it into two Apple stores. They plug it in to a TV on site, and it works fine. Take it home, and I have the same problem. It's been 12 months and no solutions. It's not the HDMI's.....I have a ROKU and it works fine, plus the HDMI ports work with everything else. I can watch TV without a problem.

Any answers as to why this unit will not work. It connects to the internet, displays the menu, but it is simply unwatchable.