This is relatively simple once you learn Scorpio's attack movements but if you're stuck, you can always come back to it when you have more health and better armor.
Scorpio will start off by firing homing saws at you. Rush up to him and stay at his side, watching out for his tail (you'll know just how far away to stand after a short while). Whack at him with your wrench and he'll mostly keep trying to fire saws at you unsuccessfully. However, he does tend to switch to his other attack once his health gets low: the dual flamethrowers. Keep on the right side of him and hop over the fire, staying to the right of it so you don't get hit by the top flame. Keep smacking Scorpio with the wrench until it falls.
Keep in mind you cannot use any protective weapons either so no Holo Shield or Tesla Barrier.