I'm sorry you've had this experience. Many here would tell you that the wise thing to do is return the tv. Look through the threads on this forum. Many problems which are not taken seriously by Roku. People are ignored for months (even years). No formal bug tracking.
As you browse a couple pages of this forum to get an idea of how you'll be treated as a customer, when you see Roku-Danny & Mary's posts, click on their username. Then look at their recent posting history. You won't have to look long to see what to expect. ("Thank you for reaching out. We suggest contacting the tv maker.."). That's the answer even when it's Roku's untested software updates breaking tvs.
In your case, that reply would be valid. You just bought it. It is under warranty. You should assert your warranty. That's going to be the clearest way to keep your options open (rather than spending months waiting for something that rarely comes here.).
I (and I'm sure others) would take that point further and say, don't let your return window run out. That's probably going to be your best bet. Even if you get the tv maker to fix it, you're risking further problems. As you can see (browsing the forum), you'll be left to die on the vine. Roku doesn't take these things seriously. The customer comes last.
Honestly, you shouldn't have to start a warranty claim with a tv out of the box either. Just return it. If they can't get it right out of the box, why try so hard when they won't? I wouldn't even mess with it during the return window, if it's already having issues.
"People are often amazed at how much we’ve done with the number of engineers we’ve got." (Roku CEO Anthony Wood, Austin Statesman, Oct 4, 2019). "Amazed" is one way of putting it.
