Help & troubleshooting for network issues, including connecting your device to your home Wi-Fi network, connecting to public networks, troubleshooting wireless issues & ethernet connections, and optimizing streaming performance.
Do you have a known good HDMI cable? Did you try a different cable? Do you have another device like a Blu-ray player you can use to verify that the HDMI input on the TV is good? Have you ever connected anything to this TV? Do you have another TV you can try? As you can see, the list of troubleshooting steps goes on and on.
The same thing happened to me so I went to my television setting, scrolled down to : (About) clicked on it and scrolled down to Restart and clicked. Your television will restart. Now reconnect the Roku and it should work.