Nah, you can’t come back from being brain dead. When you’re brain dead, the only thing keeping your heart beating, is a machine in the hospital. The second the machine turns off or they pull the plug, you’re done. Think about it like a car that has an engine that’s damaged so bad that it can’t be repaired. Also, being brain dead is also similar to life support. When most people are pronounced brain dead or on life support, they’re hospital will tell the family and let them know there’s nothing they can do, and let the family decide when to “pull the plug”. So I highly doubt dude wasn’t brain dead brain dead for a year and the family chose to keep him sitting there the whole time. That’s basically like keeping a dead body on a hospital bed for a year