Patience is going to be the key here. The parrot needs to learn to trust you and adjust to his new surroundings. Take one day at a time and slowly earn his trust.
Is the Hahn's food motivated? All it took to make friends with my Noble macaw (sub species of your Hahn's) is to feed him something he really liked. Find out what "high value" food he loves the most and feed him by hand that favorite food.
Jake could be hormonal, scared, shy, cage bound and probably all of these combined. He will need time to settle in and you will need to earn his trust. The way to a macaw's heard is though the crop. Feed him by hand what he truly loves to eat.
Parrots do not change personality overnight like your neighbor said about Jake. With him being plucked (bald belly) I suspect hormones might be at play here. Since he has pin feathers that is good news that the hormones finally dropped low enough to put the system in a moult. The moult makes most parrots crabby because it is uncomfortable for them even my even tempered Noble who anyone could handle was a bit "off" when he had pin feathers everywhere.
This might sound a little crazy but try singing softly to him. Sit next to his cage and sing and talk softly to him without actually making hard eye contact with him. He needs to get to know your voice and presence and learn that you will not hurt him. In essence you will need to tame him.
When I took delivery of my baby RFM Valentino he had been flying since 8am that morning. I picked him up at 1:40pm so he had quite a long stressful day as it was. Valentino was almost 4 months old just weaned baby RFM. On the long drive home I sat in the back seat with his carrier the door facing me so he could see me. I sang to that bird all the way home. After I got him home I set the carrier on the kitchen table and it took me 20 minuets to cut off all of the zip ties the breeder had on the door to keep him safe. I sat in a chair so I was the same height as the carrier and slowly opened the door. As I talked softly to him I slowly offered him my hand to step up on and gave the command and Valentino stepped up onto my hand like he had always known me. What helped here is Valentino was well socialized before he left the breeder and I took my time with him going at his pace.
After I took him out of the carrier I just sat there in the chair with the parrot perched on my hand and slowly sang to him. I talked to him and petted him my movements very slow with purpose. I have a video of this day that Lupe had took with the camera but I am too embarrassed to upload it because I started crying. I was overwhelmed with emotions with Valentino's homecoming.
The parrot that adjusted the best in my home was Mihijo my noble macaw. The worst and longest adjustment I experenced was with my Eclectus Joaquin. It took him 3 months to adjust. My hands use to be so sore from him biting me. Joaquin ended up being the best therapy bird I had. The work you put into the relationship you eventually will get back but it is the work and time and patience that most people can't handle.
Please keep us updated with Jake's process. I have a soft spot for Hahn's macaws.
