If you connect your iPad Mini 1 with the USB cable to your wall charger or PC/Mac, you may hear the vibrator turn on and sound and then you have changed the LCD/Glass assembly to make sure it is not your LCD or backlight film and, yet, you still have no screen or dim screen then you most likely have a backlight problem.
New iPhone iPad Mini 1 Backlight Diode for Motherboard Repair.
Repair your backlight issue in your iPad Mini 1.
Ideal to replace missing, burnt, failed Backlight Coil on iPad.
Product compatible iPad Mini 1.