With Sallybird, who was cage bound, and wouldn't even come out of the cage for 8 months... I ended up toweling her, and carrying her around in a towel for 20 minutes at a time feeding her treats and talking to her, and then setting her back down on top of her cage...
Several times per day.
It's a drastic thing. And the bird ISN'T going to like it, but after about two weeks of this, I was able to stop toweling her, and wrap the towel around my perch arm and step her up. Same routine... walk around and feed treats, then put her back.
Then, after about five weeks, I was able to step her up with my bare hands...
Then, after about two months (eight weeks) I took her out and about, and trained her to go outside and stay put with me. She got used to strangers, and got to the point where she loved it. (4-5 hours per day outside in strange places on the weekends.)
THEN, my daughter worked with her. And she began going back to the rescue, where everyone handled her.
And she became something of a local celebrity because she was the bird everyone (except two of us) had given up to, and ended up being a love everyone bird...
SO, no, I think it might be time to take drastic steps, but I would like to be there to see how she responds to it.
I am not above toweling if, and when, I have to.
It's not a first resort.
I would make sure this bird is clipped first, or it won't work.