@Percival the great, I have a DNA-sexed male Senegal, Charlie, who is approximately 30 years old. I am his third home. I have had him three years. I am in contact with his previous "keeper" who had him around 25 years. Charlie was always clipped before I got him, and he had a really short clip when I got him. It took nearly two years of molts to get all of his feathers back in full. Wahoo--Charlie will fly now, finally! Nope. He went 27 years without flying, and he saw no reason to start then, just because he was fully feathered.
Charlie's cage door was and is always open. (I cannot say that I recommend this.) I have lots of branches around the house for them, too. My house is open-floorplan, with high ceilings. I live in their aviary.
I got him a companion Senegal, George, who turned out to be Georgia. She was about 10 years old, and was
never clipped. She flies like an ace fighter pilot. Well, she quickly became scary to him. It was just too much difference in their abilities--and she was too confident, to the point of seeming aggressive.
I got Charlie another Senegal, Fletcher. (I was not seeking one; but, Fletcher had/has a special behavior problem, making rehoming him really challenging, so I decided another Senegal could be good for things here.) Charlie and Fletcher became fast friends and even allopreen sometimes.
Charlie seemed to be inspired by Fletcher's flight, versus being scared by Georgia's. (The fact that he trusts Fletcher seems to matter.) Charlie started trying to fly,
as transportation, after seeing Fletcher do so countless times per day. Short trips, and Charlie's landings were a bit awkward, but he kept at it, only flying a few times per week at first. Now, he flies a few times per day, and his landings are better, but still need work.
His general confidence has improved so much. Environmental "things" just do not scare him like they used to. It is amazing. I am so happy for him. It took a year, with lots of opportunity, and a conspecific buddy to inspire Charlie.
I was fairly passive in this process. If you want some inspiration for taking a more active role, watch this: