High Templar Avarius reset?

My wife and I have been progressing through Act 5. In our attempt to kill High Templar Avarius, my wife was disconnected. My wife was unable to rejoin the fight before I managed to kill High Templar Avarius and complete the quest. She is now unable to complete the quest because the map will not reset and/or the boss will not respawn. We have tried to separate from our party and she has tried to log off and back onto the game but it will not reset. We are at a loss.

you have to reset the entire zone, not just the boss room.

if you need to force spawn a new instance, hold control when you click the doorway into the zone (or when using the waypoint). this will bring up an interface to spawn a refreshed instance.