Why does MacBook think it doesn't have a battery?

Asking this question for a friend of mine. Computer in question is a white unibody MacBook, purchased about 6 months ago (so still under warranty, I'm assuming). First symptom was that the battery charge indicator in the top bar said that the battery was at 0%, even when it was fully charged. After plugging in the AC adapter it said that there was no battery and the power source was the AC adapter. I figured the easiest thing to do was an SMC reset.

After the SMC reset the computer doesn't think it has a battery at all. The computer will no longer turn on unless the AC adapter is plugged in, and will immediately shut off if it is unplugged. This computer has never been opened, so is it possible that a battery connector would have come loose? Is this something simple, or should I suggest that she take it in to the Apple store?