Why didn't Harry Potter die in the 7th book?

My brother and I were having a debate about this today. He said it's because Voldemort used Harry's blood to resurrect himself therefore Harry couldn't really die, but that makes no sense. How does Harry's blood in Voldemort have anything to do with keeping Harry alive. It should only affect Voldemort. My theory is that Harry was a master of death because he was the true owner of all three Deathly Hallows. So when Voldemort killed Harry, the wand wouldn't kill it's owner so the wand only killed the PART of Harry that was the Horcrux, the part of him that was Voldemort. So Harry never really died, only the Horcrux did. So that's why Harry went into some sort of Limbo state. And he came back because he had mastered death by having all three of the Hallows. What do you think?