Instax Mini 90 Neo Classic is Draining Its Li-Ion Battery(ies)

We have and love the Mini 90 Neo Classic. Unfortunately, it's started eating batteries and can't figure out why or how to diagnose and fix.

Here's what went down: went on vacation and forgot the Li-Ion charger. When the battery died, I bought an aftermarket charger that swelled and destroyed the original battery. Ordered off brand replacement batteries off of Amazon. They powered the camera on, but would die within hours if left in the camera whether camera was on or off. Ordered 2 legit Fuji batteries and same thing.

So, it's the camera. Seems that a rare few have had this issue, but I haven't found anyone who has found a solution. Needless to say, the fiance is quite displeased about this 😬 Happy to tear into, but need to know what I'm looking for first.

Thanks!