Tip: to make the battery a bit easier to pry off, try warming up the battery and the phone under a hot blow dryer for a couple dozen seconds.
After I replaced the battery, my phone wouldn't turn on. I plugged it in and and got the Apple logo, but it kept turning on and off. I put my old battery back in and it powered on without it needed to be plugged in. Battery was DOA. Hoping to get a replacement for my replacement to see how it'll work out.