Both screens not working

My husbands iPhone 5 wasn't charging so I replaced the charging port, that didn't work so I replaced the battery. It seems to have worked because when it plugged in, the computer recognized it and it made the charging sound - but the screen was completely black and pressing the home screen didn't beckon Siri, so we thought maybe the screen was fried. I wanted to see if it was the screen that was bad, or if it was the motherboard and we should just scrap it and get a new phone, so I swapped the screen with the one from my phone. Now my screen won't work! Neither work. My screen is black but my phone is still working, and I can get Siri by pressing the home screen. I'm assuming that it was because my husbands phone was still powered on (but we couldn't tell) and it friend something. Is this something that can be fixed?