Have to hit power button then home button to see display after boot

I have a iPad mini 4 that just had the LCD screen replaced on it. When booting up you see the apple logo, then it goes to a black screen. I must hit the power button first, then hit the home button to be able to see the display. It seems to work ok after I do this, but I want to know why on boot up I now have to hit the power button and home button to be able to see the display?