Stalone,
Your symptoms have me guessing 2 things.
1: Something is not connected or reassembled correctly, possibly causing a short and resulting in the discharging that you are describing.
2: It's possible that your charging fuse is blown (possibly caused by a short?)
Disassemble your phone again and reassemble, being especially mindful of any contacts that may touch the frame or case that shouldn't. While you're in there, check your fuses. See [http://www.ifixit.com/Answers/View/53447/No+Power,+No+Charging,+No+iTunes|oldturkey's answer] for fuse location.