Dornier do-27 radios and circuit breakers

It seems that I can't get the master avionics circuit breaker to turn on (stay in the IN position). It's the only breaker on all the different variants that won't click in. I can't get awos/atis nor use the nav radio because of this. I haven't even tried pro mode yet so it can't be that I broke it and it needs maintainence. Could I get a little help here? I know I'm missing something. The before startup checklist says to turn off Master Avionics switch before engine start. Is this breaker the switch in question?UPDATE: Disregard folks. It turns out I DID need maintanence after all. All is well.