May I suggest that you place a spraybottle in that room so he can see it.
Get a new one with a different color, that is important. Place it pretty far away from him. After one week move it. (or if he ignores it totally)
Continue doing that until he don't care or look at it. Then place the bottle near his cage. And let it stay. Place something he likes on top of it. (or attached)
For every time he ignore and don't care, place new treats. Also spray with it when it's empty so he get used to the sound too but only when he ignore and are far away.
You can also cover the bottle with a blanket and let him get used to the sound when he is eating some treats.
I have taught two birds to accept spraybottles with this method, both was abused with a spraybottle. One was terrified, and the other one did go to full attack-mode as soon as she saw it.
I always think it's worth a try to make them accept things in our home. And for their sake knowing that the past is the past.
My zon loves the spray bottle, her preferred way to shower, my grey,, ehh, he's ok, not a fan of it, but accepts it.