You will be spawned outside of the door and you will NOT get the catalyst for Dead Messenger after self reviving. I got the associated triumphs for doing it but was locked outside and couldn't collect the chest at the end to get the catalyst. Tried killing myself repeatedly to no avail. Also checked the postmaster and no luck there. Please make the door open after the boss is defeated so others don't waste a run like I did. In the meantime folks should just allow their teammates to revive them to avoid my pain