Second opinion; failing power board?

Working on a Toshiba television brought into my shop, and I think I have a diagnosis, but I would like a second opinion. It seems like everytime I get a "I think this is it" on a TV, I am wrong. 😅

The TV powers on and works just fine. But after around 5 minutes (inconsistent, sometimes quicker, sometimes slower) of use, the screen goes completely black. The sound continues and the flashlight test reveals the image is still being displayed, just not illuminated. It can be turned off and back on and instantly get the image back in full, but it goes black after approximately 5 minutes again.

Doing some testing, turning the backlight down to ~25% or below (by default it is at 90%) prevents this behavior and it works for at least an hour during testing.

I've checked the voltages on the board with my multimeter in DC and all power is flowing at the rated numbers (i.e. 12.74v for 13v, etc.). But perhaps if it is a random occurence of the power board stuttering I just have not caught when it happens.

Only other thing I can think of is if the LED strip is somehow failing and causing this. But I've never heard of an LED dying but still illuminating for a short amount of time or indefinitely at a lower voltage.

But... then again, I always mess up TV diagnosis, so there must be plenty of things I've never heard of.

Any thoughts or ideas? Further ways to test to verify a specific cause?