Replacing a failed E2600 controller with a "used" controller

We have many E2600 units in house. Some of them have been retired to be used as "spare parts" for the units that are still running. Now we have a situation where one of the controllers in one of our running units has failed. I was hoping a repair would be as easy as just taking one of the controllers in one of our spare units and swapping it with the failed controller. But it seems that the spare controller still has some previous configuration, or mismatched firmware, and inserting it into the running unit causes problems. Is there a way to prepare a "used" controller from a spare unit so it can be used to replace a failed controller in a running unit? The running unit is still working fine, just has one working controller (and the associated many warnings in Santricity).  Thanks in advance!