Hi @Mark34, welcome to the community.

The best steps to take to fix this are to remove your TV’s power for at least 30 seconds and check that your HDMI connections are secure. Reversing the HDMI cable can sometimes help too. If you continue to have problems, however, it’s best to get in touch with our technical support team while you’re with your system, so they can get diagnostics from it and try some real-time troubleshooting actions.