Trust me, I know how you feel and so do many others here!
1. Could be adolescent hormones like SilverSage said. In that case, a little more cage time when aggressive. Have you tried training him? It gives his mind something else to think about and helps build your bond. Is he getting good, undisturbed sleep? That is so important! When Rio was going through this I moved her into a sleep cage in a quiet room to do 2 things...get great sleep and to lessen cage aggression (which you don't seem to have). Moving his cage to a different location could help...shakes things up!
2. Food! I just read an article about this and if he has a favorite food, offer him that plus one or two things chopped up small that end up "clinging" to the fav food. He will get a taste of it and then possibly love it! Don't put a whole bunch of new stuff in, just a taste. Don't give up... Rio acted like strawberries were evil and now devours them! Have you tried making bird bread? It's a great way to sneak in veggies (using puréed baby food veggies). I put a little seed in there because she wants those badly.
3. Be consistent with your cues. When he bites, a firm no and then put him down. I turned my back on her and walked away, which she hated. A bad bite=cage time not in my sight. A few minutes later I would come back and offer out, any aggression and I walked away. When he bites, don't scream ouch...that is a reinforcer for many...they got a response. Have you tried pin pointing the "antecedents", what happens before, a bite? I know for me, I was nervous when I thought she might bite and that stressed her out...and she bit!
These guys are great, but complicated! Trial and error apply here and it's important to remember how complex they are. They are very adept at knowing our slightest mood and act accordingly. It won't last forever and your bond will be stronger for working through this. I was a human pin cushion for a few months, mostly because I was a slow learner! Once I really analyzed, experimented and worked for the desired behavior things changed, but it was hard work! When your baby starts to grow up you start a new chapter of interacting with them...but that doesn't mean it isn't still a great, loving relationship!
I hope this helps!