What The Hell Battery disabled Keyboard?!?!?!

[lightninjay]

Yeah, the phenomenon you're experiencing has to do with the construction of the Touch Pro.

The keyboard's ribbon cable is quite literally right behind the battery compartment and the only thing separating the two is a flimsy piece of metal that easily flexes to <sarcasm> quite conveniently </sarcasm> pop the cable off of its connector and thus disabling your keyboard.

The issue you most likely experienced was a slight mis-seating of the cable and when you removed the first battery to replace it with the other, the cable set itself back into the connector.