Oscar is only young and is probably going through bluffing. He doesn't hate you, he is just testing you.
When you go to step him up, be rather dominant with your approach, use a strong command in your voice, and push past his bite, to force him to step up.
(note: if he is scared of your hands you need to find a way to take that fear away. Maybe making your hands into a fist so they are not so scary ?) But then again, time will show him that your hands won't hurt him. So persist. It could take many months of persistence.
It's a very hard thing to do, as most people don't want to scare them or be bitten, but you have to show him who is the boss, and if he bites you, don't show him it hurt, do not back away and not try again as he will have gotten his way and will keep doing it.
Also, if he does step onto a stick, take him away from his cage and try stepping him up in a different area, alot of IRN are very protective of their cage, especially if they are in sleepy dreamy mode (having a nap or on dusk ready for bed).
Remember IRN's have moods, sometimes good, sometimes not. They all have their off days and bad times.
Our Jordan is the tamest thing I have ever seen in a ringneck, we can cuddle him, hold him, pick him up by his body if need be, I can hold him in my hands and kiss him all over, but he even gets snappy when he is resting in his cage. I don't let him get it over me, i force him to step up as I don't want him to have any area that I cannot retrieve him from if necessary. Some say that they need their cage as a safe haven, retreat, but I don't believe this. They know I love them and they know I am boss.
Good Luck !