Let's check if the iPad has a no backlight issue. First of all, plug the iPad into the computer and open up iTunes, if it boots up it should detect the iPad either as trust this device or locked with a passcode.
If iTunes detects the iPad then you probably have a no backlight issue, you can confirm this by shining a flashlight on the screen and see if you can see anything on the screen.
Backlight circuit goes bad when you unplug or plug in the LCD screen display cable while the battery is still plugged in.