I think yes it's possible
I also have a 2 year old untame African Ringneck

I talk to everyone I met that has had or worked with ringnecks, and the general consensus is that it just takes longer than it might with a different species.
My parrot Cotton has lived with me for 6 months now. At first he would move away the second I came in the room. Now he'll take walnuts from my fingers: )
He still does NOT want to be touched but he definitely trusts me and doesn't move away from me any more unless he thinks I'm going to try to touch him.
Have you read about clicker and target training? This can be a really great way to establish communication about what you want and what she'll get. Cotton has been very stubborn about targeting this so far

but he enjoys the hands off training we have done, so we'll get there.
I've heard from several people that taking a year for basic targeting or treats is not at all unusual, so hang in there.
With Cotton I started by using a separate little metal bowl on the door of his cage, only for treats. This way if we're working on something I can say "yes!" or use a clicker and drop the treat in the bowl, back away, and let him get the treat.
My goal with Cotton this coming year is to get him to target into his travel cage so we can go outside next summer. I don't know that he'll ever choose to step up on my hand but he might onto my arm or a perch.
I have to admit I love how stubborn my little man is; he is ALWAYS studying me and will take advantage of me if I let him - like he'll always pretend he won't take a treat from me, waiting to see if I drop it instead. So I kind of feel like the general idea that ringnecks become untame again is because they're so good at training us
Welcome to the forums!
I would love pictures if you have them; as you can tell I get super excited when I "meet" another ARN person!!
Denise and Cotton