Vizio P502ui-B1E doesn't turn on?

Inhereted a broken Vizio P502ui-B1E 4k TV from a friend who already purchased a replacement. The power LED turns on for a few seconds when I press the power button, then it fades away; the screen is always dark. (Friend indicated that according to his research he needed to replace the power board, but doesn't have the expertise/time/interest.)

I took the back off and measured a few of the supplies on the power supply board. There are (at least) three labeled power supplies on the board: 24V, 12V, and 5V, which go to a couple connectors, which is the easy place to measure them, aside from the (unlabeled) electrolytic caps. 24V seems to be up, and 12V seems to be up as well. The 5V supply seems to not come up at all; I don't measure anything on it. (though i imagine that this would have been the supply that feeds the LED, but who knows; I didn't design this thing and finding schematics seems to be difficult.)

Rather than dig in without a schematic and try and replace individual parts, I took a shot in the dark and ordered a replacement power supply board on ebay for $40. Hopefully, the 5V supply blew on the power board and not for something downstream, and it will be worth a $40 gamble for the potential of a better TV than the one I have. lol.

Anyone have this issue with their vizio before?