Replacement battery wont take charge.

I recently replaced my 3GS battery with the iFixit replacement. The install went smoothly and the instructions were great. After reassembly the phone it started right up and showed 100% battery life.

I continued to use the phone for a full day and noticed that the battery percentage never changed from 100%. By the end of the day, unsure of how much life was actually left in the battery, I pluged the phone into the wall to charge over night.

The next morning I removed the phone from the charger and used it for about 10-15 minutes and it died.

It displayed this screen when I tried to turn it back on:

http://km.support.apple.com/library/APPL...

I attempted to plug it back in to charge again seeing as it was telling me the battery was dead, but no matter how long I left it plugged in it would not take a charge.

I have since removed the replacement battery and re-installed the original battery and the phone now works as normal.

Any insight as to what this may be? I checked the screws under the do not remove sticker and they were tight.

edit: software is IOS5