The TV shouldn't have anything to do with it. It would help to know the model number of the Roku device (written on it somewhere) and whether or not you have a voice remote (with a little microphone button on it). Voice remotes have to be paired with the Roku device before they will work. Devices get added to your account once the setup is completed. There's no other way to do it.
It might also help to know why you factory reset it. Was there some problem that you were trying to solve that may indicate some issue with the Roku device that's preventing it from connecting?