Dead after battery replacement

I replaced the battery in my Iphone 5S, but it won't power up. But - it seems to be charging because the phone is warm. The fact that it gets warm makes me thing the battery is plugged in OK. I carefully put it back together following the excellent guide. I did not tear the home button cable or other cables.

Any ideas would greatly be appreciated. I'm feeling pretty frustrated right now.

Thanks,

Brian

I got the phone to come back to life by unconnecting the screen, battery, and home button, blowing out dust, and putting it back together.

The issue I have now is that the screen is flickering (looks like a slow refresh), and has some squares across the middle. It also has some vertical bars running from top to bottom. Any ideas?