Besides the talking at the cage, etc. I do have a few things that have worked for others including myself. Adults do take longer than just weaned - so patience. He should come around.
1. Eat your dinner next to the cage. In fact, have some brocoli and other veggies on your plate and make sure he can see you eat it. Just Mmmm, and Ahhh about how good it is. Don't offer yet. Do this for a day, 2 or even a week. Eventually, he may even come to that area of the cage you are eating at and "ask". After a few days, just simply ask - want a brocoli? if he doesn't move. "It's ok, maybe next time." then just eat it.
2. Learn to stick train your bird when you are ready and HE is showing more and more interest. There may come a time when he's on the floor and you are scared and instead of showing fear, you pull a stick perch out for him to step up on.
3. Toys. Petrified. Even to this day, our Suki Dew is completely mortified on some of the toys. So, like a darn fool, I have to hold the toy, play with the toy, move MY nose through it. Grab with my teeth and swing it violently. My wife laughs like hell. But no kidding - if not within 30 mins, she is WITH me picking up one block while I pick another and we both play. Before the day is out, the toy is in and she is buried in it.
Patience. Once he trusts, he'll be around.