Random iPad Air Screen Locks

I recently replaced the screen/digitizer and battery on my wife’s iPad Air. Everything seems to work normally except the screen will turn off and lock at random times, including while my wife is using it. It has even turned off multiple times in a row (in a matter of seconds). She has to hit the Home button and enter her pin to get back in. It appears to happen more often when the battery is low (below about 30%?). I’ve tried turning off Lock/Unlock and setting Auto-lock to Never with no effect. Any thoughts on what might be causing this?