Molten Vault - Mektul the Forgemaster - Cruel

I just finished the bossfight and it happend that the boss an I died at the same time. Now i can see the "Hammer of Kamasa" laying at the bottom of the fightingarena, but i cant get back down, because the elevator is disabled now, that the boss is dead.
What can I do now?

Im sorry for your loss, but thisi is intended gameplay. you could also die to adds after the boss died, and the loot is gone. happened to me too ^^