Apple TV login on TV following change of password

I changed my Apple password and now I can't access Apple TV on my home TV. I did get a QR code which I thought would enable me to login using my new password but now all I am getting is a message saying 'could not connect to Apple TV. Check your internet connection and try again.' My internet is working properly. I have shut down the TV and my router to reset everything but I'm still getting the same message. How do I login again on my TV?