I'm Not Dead

After waking up in his coffin, Elliot discovers that he's alive and well, even though he knows he died. He doesn't remember much from when he was dead, but what he does remember is that he has messed up.
Now the town believes he's something demonic, his girlfriend is convinced he's not real, and his best friend still doesn't quite believe that he's back. But what happened in his afterlife that brought Elliot back to life, and what did he bring back with him?