2DS XL blue light turns on, but screens don't turn on.

Hello, I purchased a bundle of 2DS XL systems but a few have issues working. When the power button is pressed, the blue light turns on but the screens do not light up and there is no sound. Is there any way to fix this?

I have opened some of the units in an attempt to repair them. I disconnected and reconnected all cables but there was no change.