Audio- "ERR" code
 

Hi-
I have a 93rx7 with the Bose system. Often when I pick up my car after a repair from the shop (non-dealer), my radio displays "ERR". I know that whenever the battery is disconnected you need to enter a code to unlock the radio. However sometimes it asks for the code so that I can unlock it and other times it goes right to "ERR" mode. Then I have to go to the dealer and pay and wait for them to unlock it. What a hassle! Does anyone know how I can unlock this "ERR" code?
Thanks!
Bob Kennedy