I understand, and I know it can be very frustrating, we've worked through it as well

, and at that time Stitch lived in our living room, just as your guy.
Thing is, dont react in any way, not even by leavning, but continue doing what you were, and look like you ignore him (then you can sneak off). Then immediatly on him making the nice sound you're training praise him.
Screaming can go on for hours, so you need to be prepared for it. In our case it was never more than 10-20min, for which im thankful for, but it can take a lot longer than that - like I wrote, it can take hours. I advice you to invest in ear plugs (they can come in handy with parrots, leroy screams like all hell is loose when showering, but still loves it lifting his wings and preens at the same time ^^).
The key to get passed this is to be consistent, do the same thing everytime. Dont change tactics if you cant see any results in a day or two, it may take several weeks for you to notice a difference.
Patience in abundance is required with parrots!