Citadel bug with doryani

I defeated doryani in the citadel and got the fragment from him but while i was colecting loot from him one of his attack remained in the arena a trial of lighting from above killed me although i defeated the boss. After i respawn i was still able to do the boss, while i was fighting with his 1st form, the robot from the 2nd phase was laying dead in the middle, after I get to the 2nd form once more the game buggeed and i couldnt damage the boss and now im stuck in the boss arena.