banding on screen, went black after 30 mins

Hi All,

My 27 apple cinema display was temporary workingONLY with an external thunderbolt cable to the back of the monitor, but it had banding issue like this on the screen.

Now after using the monitor this way for 30 mins, the monitor went completely dark and will not power back on. I can still detect the monitor in the display profile under preference.

I have tried PRAM, latest firmware.

I have already replaced:

1. Magsafe / thunderbolt cable, but the thunderbolt part of the cable is still defective, the magsafe however works fine.

2. 922-9942 LVDS Displayport Cable.

Here are my questions:

1. Since the monitor won't even turn on by plugging in the thunderbolt cable in the back, could it be the logic board? but my computer can still detect it under preference?

2. The banding issue in the pic above, is it a seperate issue from the logic board? is it the LCD itself or just that little board attached to the LCD?

3. if it's not any of the parts above. Could it be the power supply board? My gut is saying no, because my magsafe cord is still working?