I would block him until he is trustworthy. Since he clearly wants to be with you and bites when you assert authority, I would not react to the bites other than walking him to a time-out location (if you must say something, say no in a neutral voice (or, "be gentle"), but it depends on the bird---some love any reaction). NOTE: If he were biting out of fear etc, this wouldn't work (because then he would be escaping and getting his way), but since he is clearly not afraid, I would say that time-out for a few minutes or so should work (maybe 3-5?---no attention during this time-don't look at him or talk to him). You could even set a timer. When the timer goes off, pick him up and repeat as needed. If you can pick a cage besides his for time-out, that would be ideal, that way he doesn't think cage=punishment. Soon enough, he will associate biting with removal from an otherwise good situation. Practice following step-up commands off of the shoulder----if he has a favorite treat, use that as a reward. In a pinch, try sitting on a couch or backing up against a wall to force him to step from shoulder to hand (DON'T SQUASH HIM LOL!!!-DO NOT LEAN AGAINST HIS BODY...)