Screen randomly goes black; not fade to black.

Mid-2012 rMBP 2.7 So I thought every so often I hit a hot (sleep) corner or something but the laptop wouldn't turn the screen back on with any keystroke or power button. That said, if you held a random key down, you'd hear the "sound" of holding a key down so obviously the laptop was still on. It would take a full restart to get the screen to function again. Didn't think too much about it until it started to happen more and more frequently and got to the point where I'd be in the middle of doing something, the screen would turn off like you flipped a switch, and no matter what you did, wouldn't come back on unless you fully powered off and then let the computer rest for 15 minutes or so. Then it might stay on for 5 minutes or for 5 hours. Plugged in or not plugged in, full battery or not, nothing made a difference now that I was specifically watching for the issue and noting what I was doing and how charged the battery was, etc. Now at the point the screen won't stay on for longer than 5-10 minutes. Genius bar was (ultimately) no help. They ran their battery of tests which recommended they run the graphics test but by this time, the screen wouldn't stay on long enough for them to run even that. Their diagnosis? Logic board replacement thinking whether it's related to the graphics card (which was recalled on this model previously but they won't honor this late in the game) or screen interface, either way that'll fix it. $550ish. Sent laptop out yesterday instead to PowerbookMedic for $345 for logic board repair service. Will advise how this all turns out...