Quoted from Zitt:So far I am not sure, what problems exactly happen, when this battery gets empty.
The battery on the mobo holds the CMOS mem, so you'll lose CPU date/time....probably will still boot, I've never actually experienced it, but it is just a PC- I don't think there are any special settings in there that are required to make it run. The battery on the Prism would be holding the game settings, so likely everything would default, you'd lose things like the high scores, freeplay settings, # balls etc.... so that's how you know which battery has failed.