MacBook shuts off- Only with new battery connected and cover on.

So I had a spill... I know. The good news is the damage was contained to wifi card and keyboard. I swapped out my lower case assembly, but while doing so ripped the battery cover and the next thing you know I was ordering another battery from here. I reassembled everything, got the green light from the charger and the machine booted up, and it worked! But when I put the cover on, the laptop wouldn't turn on anymore and I had no lights from the charger. So I unplugged my battery waited until the capacitors ran out of charge, and it works without the battery connected and the cover off. Currently I'm still endurance testing it.

Things I have checked:

-No visible Water damage

-Fans Working

-Thermal Paste Applied

-Wifi card still broken (gonna buy a usb thing)

I am clueless at this point. Could the battery be faulty? Its the only viable option. School has started once more so I need my laptop asap :'( Please help!

Update: The endurance test on the charger has failed, and the system has shut down.