Elizabeth bought a used MacBook Air, and when she got it, she wiped it. Now it doesn't work right. Leo suggests signing into iTunes and redownloading the OS update and installing it. But she can't turn off the firmware password utility. Leo says that if she can prove ownership, Apple will unlock the laptop for her.
It sounds like Elizabeth has fallen into the trap of Apple's Activation lock. Here's a few tips on how to wipe out that firmware password from OSXDaily.com