We would recommend performing a factory reset on your Roku TV and see if the TV will update to the latest OS. Please also make sure that you have a stable internet connection when activating and updating your Roku TV.
Perform the following steps with your Roku remote or the Roku mobile app.
Press Home on your Roku remote
Scroll and select Settings
Select Advanced system settings
Select Factory reset
If you have a Roku TV, select Factory reset everything. Otherwise, move to the next step.