If you're right, I would guess that there's an internal part that is shorting the battery to the case. You could test for that with a multimeter. Though, that seems unlikely unless something got inside the case. A wonky battery seems more likely to me. If you have an AD in town and they just replaced the battery, I would be inclined to go back to them and describe the symptoms and see if they have any ideas and/or are willing to deal with it. Seems like they'd be at least willing to put in another battery for you, and you'd at least have another data point to work with.