@JennSm , I haven't done this. But, I thought shopjimmy has that info (which parts go for which tv models.). Seems like they'd know what a particular brand/model uses (or what you need to look for. A part number on an existing strip?).
I would think that the hard part is determining whether the problem is one of the boards (power, tcon or motherboard). Or, if it's one of the backlight strips. I've seen videos showing how to narrow things down, but you need some tools.
I've seen shopjimmy sells all the boards as a package. The idea being just replace them all for $50, and cross your fingers. If that doesn't work, then replace the strips (assuming SJ knows what you need, or how you can discover what you need). It looks like a person could have $120 USD into all of that.
I think the risk would be that something is definitely happening with Roku's software updates (breaking tvs). Some kind of hardware variation Roku didn't test for. Maybe a revision to a tv model, a board in a model. Nobody knows. Something like that is definitely happening. So, if the black screen were due to that, it's possible all the new parts would be the same revision, and same problem. Nobody's trying to understand what the failure is with Roku's software. Roku blames tv makers. They blame Roku (rightfully). Another risk would be that one of these shotgun-approach boards/strips would fix the problem, and then the next untested Roku software update would break it again. IMO, the only way to safely use a Roku TV is disconnected from the internet. A "dumb tv" that you stream through an external device connected to HDMI. At that point, is it really worth putting more money into?
It's the classic prisoner's dilemma. It's not fun to have such bad choices. If Roku let us disable updates, and roll back to a prior update which worked, it wouldn't be so abusive. Android does. If your tv goes black, you could go back to a prior update to see if it's black too. Then you'd have a better assurance that it really is a hardware failure. You wouldn't risk pouring money into something that the software has left behind.
"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.
