Thanks for reaching out to the Roku community!
I'd be happy to look closely to see how we can help. As a first step, could you try to replace the HDMI cable or connect the device to a different HDMI port on your TV usually helps resolve the issue?
To help troubleshoot the issue further, follow this link: What to do if you see an “HDCP Error Detected” message or a purple screen | Official Roku Support
Please let us know and we'll continue assisting you from there.