Can't restart Ogham Manor!! Boss can't respawn!!

My friend joined to help me kill the boss in Ogham Manor, midway through 2nd phase of fight my game crashed, right before i rejoined my friend killed the boss and it didn't count toward my quest and it still says I need to kill the boss but I can't restart Ogham Manor to get him to spawn. Is there a way to get the manor to respawn so I can kill him?

You can Ctrl- click from a waypoint, or when entering from another map area to start a fresh instance.