So I checked another forum post about battery problems and I figured out that we had the same issue as them. The issue is that our cell voltages have gone too low, as outlined in this post.
Here’s a picture of our battery connected to a charger:
As you can see, one of the cells is reporting a big fat zero on voltage. We’re gonna try to recover the battery with a specialized charger. Also, it’s never been airborne, we’ve only ever had it plugged in on the table for configuration. @GymLeaderBrock thinks that the battery is bad.