Wow..
You have made a quite a committment there. I hope you are ready for some challenges, because it's going to get difficult before it gets easy. Anytime you get a new bird there are surprises.
But your lack of bird experience means just about everything will be a surprise.
At this point let me point out that you are going to have to adapt to some new costs in your life. This bird will take an enormous amount of time to tame and train to make a good pet. It will also cost a LOT of money to take care of this bird properly.
If you aren't up to these, I'd suggest that right off the bat ...it would be better for everyone involved ...ESPECIALLY the bird, if you were to find a good bird sanctuary and let them assess it and possibly rehome it with an experienced owner.
If you want to "give it shot", be prepared. It won't be easy or inexpensive (notice I've mentioned this twice now ... I really mean it!). And it might be painful.. If this bird bites you out of anger, he can send you to the hospital with broken bones, or in need of stitches!
Greenwings are the second largest of the macaws, and one of the loudest! A wild one like you describe, is a "handful". Possible one of the biggest challenges a bird owner could ask for... with some of the best rewards at the end ..if you have the patience.
At thirty, this could be an imported/wild-caught bird. That, or the previous owners lack of expertise would help explain the aggressiveness. It may never be a cuddly, friendly bird.
Give the bird about two weeks to get used to the new situation. Don't try bathing the bird, just give them their usual diet ...and try to act normally around it.
You want the bird to become accustomed to the new enviroment ...the new sounds, schedules, people, etc. Talk to it in a friendly manner, offer treats when you can, but if it refuses ...walk away. Giving more attention to "bad" behaviours just rewards those behaviours.
Your FIRST order of business: You need to find a good
AVIAN vet (this is a specialty among vets). The bird needs a checkup right off the bat. Overgrown nails and beak are going to need attending to. They can be indicators of other problems (liver dysfunction for example). ..Problems that can only be detected by bloodwork and an exam. You aren't going to be able to deal with the nails and beak yourself.
A good vet ..one you are comfortable with, it essential to every bird owner. From what I've just read of the previous owner ...I'm not thinking they they took this bird to the vet very often.
Be prepared. An avian
vet visit is expensive. A good. thorough checkup ...which is what the bird needs, is going to cost well over a hundrd dollars, maybe a good deal more. ...but remember, this bird is worh thouands of dollars. It's not that much by comparison.
What's more, a good vet can help with all the problems you are about to experience. He/she can advise on diet, caging, behaviour and other issues like proper bathing.
I can't emphasize enough how important the vet is to a birds welfare ...especially in your case, as you lack the experience to recognize the early onset of some of the problems you may face.
You have made a serious committment. These birds live for up to a century.
I've had bird for almost twenty years, and greenwings are a bird I've never owned (but wanted to) ...the oppurtunity has just never been right ... I envy you ..a bit.
Good luck,
And we'll be here if we can help.
Bob