3 week old TV and as of last night I see a white dotted line across the screen. Verified HDMI connection. Disconnected all devices from TV, performed factory reset, verified latest software version.
[post moved to appropriate board]
This will probably be moved to the Roku TV board.
In the meantime see what you can find there its above or here.
Check your receipt and or warranty.
I just went there and there is a Sticky at the top on your subject.