Damaged battery after lcd replacement?

Yesterday I put in a new LCD replacement for my iPhone 4s 32 gb. The screen works great and everything else works as well after reassembly.. HOWEVER. My battery started to drain very rapidly once I powered on the phone. The phone was also warmer then usual.

It seems the battery only charges when plugged in and powered OFF! If it is on and plugged in, the battery will drain but at a slower pace.

Do you think I damaged my battery? or shotty reassembly that could have caused this problem? I was thinking I would try and replace the battery as a first step of trouble shooting.

Thanks in advance for any help