This doctor was also brain dead at one point:
http://www.amazon.com/Proof-Heaven-Neurosurgeons-Journey-Afterlife/dp/1451695195
No, he wasn't.
Here's what's happening to Jahi's brain right now. There is no brain activity whatsoever. None. It is not getting blood circulation. The cells are breaking down. Her brain is decomposing. Soon it will turn into a liquid and flow out of her nose.
She is not coming back to life.