The Nabi Jr tablet is nearly indestructible, which is fantastic for my 2yo son. The problem is their choice to use a proprietary connector that uses USB under the hood. It's a multi-pin cable that I can only assume they envisioned releasing some video out cable for, but nothing ever came of it. Because of this proprietary cable (and the fact that no one but them sells it and Nabi charges $15+ for this cable) this wonderful tablet spends a lot of time uncharged.
I plan to add a standard USB MicroB connector and possibly upgrade the battery while I'm under the hood.
I've opened the case. Was expecting trouble, but nothing more than four Phillips head screws and snap locks along the case edge. The plastic case is very thick for a tablet, so getting enough leverage to pop the snaps was tricky. Ended up with a little marring on the edges thanks to my trusty flat blade, but nothing too bad.
First sighting of the battery. I've been slightly disappointed by the total battery life on this tab, and now I see why. They could have tripled the battery capacity and still fit in the case, which is what I plan on doing. Now to find a compatible battery.
Are you sure you want to put a micro usb connector on a device for a child? Even as an adult I hate those things. they are too tiny to be durable. Since the Nabi doesn't suffer from "gotta be thinner than everyone else" syndrom maybe you could fit a real USB-B connector on there. That could probably take a lot more abuse.
If your theory that the Nabi connector was supposed to be more than just USB is true it would be awesome if you discovered the pinout for the other feature(s)!
In regards to a battery, with a minor mod to the case, a Nabi 2 battery will fit and greatly increase your run time.