Why is my screen black with no response?

A customer recently brought me an iPad Air 2 in good condition saying it just stopped working one day. There is not visible damage, and everything externally looked fine. The iPad gives no response when plugged it, doesn’t turn on, and doesn’t pop up in devices when connected to my computer. I have tried all the basic resets and just replaced the battery with the same result. I was wondering if anyone else had come across this problem and knew if it was possibly a blown chip on the logic board, a bad screen, or a battery issue. Any feedback is appreciated. Thanks!