We had an excellent tech who I could tell had good knowledge of the
product and used proper installation practices. I have some general IT
experience and we had a good discussion about the technology. It was
clear he had a passion for what he was doi...
My brother had the same issue. He unplugged then plugged back in his
HDMI cable which fixed it. Check your HDMI cable and swap or replace it.
They can be finicky and do "wear down" as they get older.