I have the i3 Prusa that comes with an LCD screen+SDCard reader.
The board is a MKS base 1.2.

In addition to a million other problems I'm having, there's some other weird stuff.

The LCD only turns on when the board is plugged into the USB.
The LCD doesn't turn on when the PSU is powered on and connected to the board WITHOUT the USB connection.
When the USB is plugged in with the PSU off, it turns on.

Is it normal for the LCD to only respond to the USB? That seems unreasonable because that defeats the purpose of the LCD screen + SD card reader which is meant to print without being plugged into the PC