Whatever you do, do not get hit. Besides that, just shoot him in the mouth whenever you get the chance. When he is stunned, rip open his chest with your Grapple Beam, go into Hyper mode, and blast away. Repeat this until he gets armor over his chest. When he is stunned, go into your X-Ray visor and shoot his shoulders. You will then be able to shoot his chest. Use your Hyper mode and kill him.