Greeting from the Roku Community, @honeqwo2!
We understand that you wanted to use the physical button on your ONN Roku TV as a temporary control to it. We'd be more than happy to suggest any possible workarounds for you to try.
As this can be more inconvenient, we highly recommend using the Official Roku Mobile App as a temporary remote for your Onn Roku TV. As long as your TV and smartphone are connected to the same Wi-Fi, you can control your TV and use your phone as a remote in the meantime.
For more information on using the app, you can visit this support article: How to install the Roku mobile app.
We hope this helps.
All the best,
Emman
Emmanuel-D.
Roku Community Moderator