Cant enter Boss fight after i killed the boss but he killed me too

I just killed Jamanra in the copper citadel. But before I could speak to Asala I got killed too so i spawned on the checkpoint. The problem is the fight counts as completed even tho I didnt speak to Asala. I cant go into the arena anymore because the bridge is gone. So basically the map counts as completed but i didnt get the loot.