I have a 43" Roku Hisense Smart TV
The screen just recently started flashing a lower brightness that kinda travels from the bottom of the screen to the top. It happens no matter what app I'm using and happens at the home screen. I have tried turning it off and on and even unplugging for a few minutes. I've had this tv for less than a month so this upsets me.
I'd be upset also.... a new anything shouldnt have problems.
Can you watch anything aside from Roku? does it happen there?
Can you try a lower resolution?
It happens when I'm using my xbox one for anything and when I'm using YouTube on the tv. But it also just happens on roku's home page. Since last night I have now found that it only happens in dark spots of the tv and it is actually harder to see at night. So it may not be that big of a deal. But it is noticeable. I'd also rather not lower my resolution. It's at 1080 for everything because everything uses 1080.