Let's go back to the original 12channel amplifier for a moment. one day it was working and another day all 12 channels are dead?

Sounds like an electronic tech could possibly repair the power supply in this amplifier while you create a backup plan.
I would like to know who built it for them.

You can capture the RS-232 codes from a variety of com programs. You can also program a controller from crestron, amx, RTI, URC to see these codes and create new codes to control a different amplifier.