The first thing I would suggest is to not push it too fast. For now, talk softly to the bird while you sit next to the cage, reading to them often helps to. . . Your first goal is simply to get the bird to tolerate you being around and talking to it. Most of the time these things take a long time with parrots and we have to let them take things at their own pace.
Right now when you go by the cage, what is his reaction? Does he bite at you? Flap around? Just watch? This will tell you a lot about how you should start off with him.
Assuming he doesn't completely flip out when you are by the cage, after you have gotten him used to your voice, you might try opening the cage door to see what he will do. Is he clipped or flighted? Clipped birds are easier to catch if they get out and don't want to go back in for sure but IMHO, most parrots are much happier and much less prone to agression when they are allowed to stay flighted.
