dexman

I don't know how available something like that would be (outside of a repair facility). Those modules are so inexpensive, replacing a defective unit would make more sense than trying to repair it.

cybrsoldr

I'm trying to refurb a board. As a hobby I can repair boards down to the component level and the place I work for found that out so they want me to refurb a few to see how it goes. They may want to start selling refurb equipment.

dexman

One option would be to simply purchase a known good unit that you don't mind prodding & poking around with (they are fairly cheap), and use it as a sort of "guide"

I suspect the schematics & documents are considered to be proprietary so contacting Avaya may be the only option.

Except for the power supply boards, I suspect that the motherboards contain mostly surface mounted components.