I'm sorry this happened to you. You're not the only one. Yesterday someone reported the same problem with a Sharp. That thread links to someone else who reported the same thing a few days earlier. I think there's another thread with other brands doing it. (If I find that, I'll update this post. There's a very long and old thread with people having a "recovery loop.").
Unfortunately, you're not going to get any help from Roku. They're going to tell you to talk to the tv maker (even though it's obviously software doing it). Roku pushed an untested update the past few months knowing it was breaking tvs. They told the affected people to talk to the tv makers (and kept pushing it out, knowing what it was doing to customers.).
There is a pinhole reset button on the back. You could try that. Additionally, you could tell the initial setup that you'll connect to internet later. That loads a smaller and less-problematic form of the software. Maybe that would work, and you could stream through HDMI. (I'm using my two regrettable Roku tvs this way to protect them from additional untested updates. I've seen others say they've done the same thing.).
I hope that works for you. But, I think you need to prepare yourself for buying a new tv. The thread I linked to talks about replacing boards. You could do that, but I mentioned there how that's a gamble because nobody knows what is incompatible with the software. You could replace boards with the same thing, and end up the same way.
"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.