A long time ago I tried charging a battery without the balance plug but it wouldn't work. That reading was without a battery plugged in. However, I think there's more than just this "output voltage too high" problem. I finally got one to start charging in "storage charge" mode. Well, it started around 3.9 volts/cell and is supposed to drop them down to like 3.6-3.7. Looked at the screen a few minutes later and they were up to 4.55 volts! I yanked it off and haven't touched it since.

I'm gonna try to update the firmware. If that doesn't do anything I'll probably just send it in.