LED Cinema Display 27" backlight problem

I have a LED Cinema Display 27" and the last couple of weeks it started having problems.

When I connect my macbook pro (2011) with the mini displayport cable, it flashes shortly and the screen stays black.

If I take my flashlight and look very closely at the screen, I can see my apps. The sound works, the macbook pro display is extended to a second screen, the usb work, etc.

So my backlight is having problems. But when I take my power plug out of the socket for a minute, and put it back, the screen turns on and it works flawless! I read some other posts with similar problems but I didn't seem to find what part to replace. The screen is still very bright, no flickering, etc now. Until the next day when I take away my macbook and come back and plug in my macbook pro again, then it happens again and I should do the whole routine again.

I want to know which part I should buy and replace?

• The power supply inside --> Don't think this is it, because my macbook charges just fine
• The all-in-one cable --> Don't think this is it. There are no parts of the cable damaged, and everything works fine for hours after the backlight comes back on.
• The LCD backlight --> It workes fine and is still very bright when the problem doesn't occur.
• The logic board --> Could this be it?