Hello I just bought a brand new Onn Roku 43” smart tv, from the moment I turned it on all I faced was problems, the TV would not connect to internet until I switched to xfinity even though my WiFi before was perfectly fine. After this I tried plugging in multiple game consoles from ps4 to Xbox to Nintendo switch, each time I plugged them into the hdmi ports I would be greeted with complete discolor or black horizontal lines across the screen then it would black out and not work at all. Other times it would say show the screen prompt that a device is connected to the hdmi I plugged it into but when I go to select the input it will just say no connection. I have tried using brand new hdmi cords for all different consoles but still nothing. I am very disappointed in this purchase if I could rate -5 stars I would.
Roku doesn't make the TVs; they only provide the software/OS. You'll have to contact onn for hardware problems like misbehaving HDMI inputs. You may have just got a lemon and since you just got it perhaps an exchange is in order.