U3011, on but no display

Working along the other day and one of my trio of U3011 goes black.  (middle one) Windows still thinks it's on and working and plugged in. Still acts like it's on (can move mouse across like normal). Windows detects it's plugged in and working. Buttons work, are lit up, and makes BEEP sounds like normal when pressing them (thought I can't see any settings being changed) will not cycle through tests (red green blue, etc) when GPU cable is un-plugged, will not display anything on the display whatsoever. no matter what.

I did NOT have any problems before hand like disappearing randomly or blacking out occasionally. No flicker, nothing, just went dark one day and never will display anything on the monitor. Windows still detects it just fine, still think's it's there, still acts like it's there. I think it was still playing sound through the DP > speakers too, but I'm not sure on that one. 

So yeah, it seems like such a great panel still and what not. I'm sure some board is fried inside, I have no qualms replacing a board or what not. I see good handfuls on eBay. Have I provided enough information that someone can tell me what board is most likely the culprit? Inverter board? Main board? power supply (Doesn't seem likley, but what do I know?) 

Thoughts? 

(I am a computer tech, so yes I've troubleshot it proper. - tried another DP port, and hdmi and everything, another computer, another, etc - I have three (well 4) of these, I at least pretend do know what I'm doing)