Yup, I let it go totally flat. Took about a week, so I know the battery is holding a charge.
The replacement battery shows less signs of damage. In the 40%-~90% range it works as intended. Shows charging when plugged in, Discharging when not plugged in. Somewhere above 90% it seems to think it's still plugged in when it isn't. So it has to discharge a bit before it will function correctly.
The old battery PROBABLY isn't damaged, but the range in which it works correctly and in correctly is MUCH more random.
I SHOULD have warrantied it before I decided to replace the battery.
I mean for the most part its fine, however, being a car install, I kind of need Tasker to work its magic depending upon charging state. And since that's messed up, Tasker won't work as intended.