When I first got Lurch the lady who had him was amazed he allowed me to touch and scratch him. I took him home without incident, even stopped by lil sisters house so she could meet the new Maxi she helped me get, no problems.
When we got home I put him on Nerds old play stand and he was happily getting a scritch under the chin when he had a thought and whipped around and tore a chunk off my finger and started birdy swearing at me. I never saw it coming and he definitely didn't give any warning I could detect after having Nerd bird, another Maxi, for 31 years.
He was mad and scared to death and I got lots of bites till we slowly became friends. He did start to give warnings again once he decided they worked and he cared for me. He never did stop biting entirely, it was a feature of who he was and I accepted the occasional pop for the most part as part of gaining his trust though trust me we had a few bad talks over time.
Hopefully someday Wasabi will become more like the loving and trusting Lurch, rather then the bite now and ask questions later version he was at first. Hang in there I think somewhere he likes you just a bit but just doesn't want to let his guard down