You can't get your local channels via an A/V port - you need an antenna. I don't know why your TV's remote isn't working, but you'll never be able to get your local channels using a Roku device or using a Roku remote. The universal remote not working doesn't have anything to do with the Roku device. Are you sure it's set up properly?
I have connected an antenna to the A/V port.
If you have something connected over an a/v port, then it is presumably a cable box or an HD OTA tuner. A plain old antenna connects to the antenna/coax connector.
In any case, since you have a TV and a separate Roku device, your Roku will be unaware and uninvolved in any of this. You'll just use the TV as you normally would, and if you want to stream later, then switch to the Roku input and use the Roku remote again.
