Thunderbolt-Display: Screen does not light up randomly after reconnect it to the power grid.

So, I got myself really lucky a few days ago and got a "faulty" Thunderbolt display for ridiculously cheap.

So far it is working perfectly, yet the previous owner told me that the screen stays dark occasionally, although the device is recognized my the Mac.

I could track down the problem somewhat to the fact, that this only happens when you disconnect the Display completely from power grid, forcing it to shut down instead of going into standby. I recognized this after relocating it to my home and plugging it in again. After a few times replugging it, it went to work again and it is totally fine.

Does anybody know what this can be connected to? Damaged inverter? As I said it works flawlessly, but I have it now plugged in constantly anyway. I just seek some more information what could come my way in the future worst case. Considering I expected to get a new panel I'm totally happy.

Thanks for any help.