Apple ID not accepted by Sony Bravia TV

My new Sony Bravia is a Google TV, and comes pre-loaded with the Apple TV app. When I try to login to the app with my Apple ID, it repeatedly refuses to let me in, saying there is a verification error and to try again later. I have updated the software (even though it's a brand new TV) and tried numerous times with the same result. So I connected my old Apple TV box, and that works. However I'd really prefer to just use the app on the TV. I've tried a number of the suggested remedies but nothing works, and also the TV settings and remote have been updated so it's harder to follow the steps as they don't correspond. Has anyone had any luck?