Interchanging RC(s) and AC(s)

Before I try this( I'm fairly certain it's ok but just to make sure I thought I put this out there) - I have a working RC & a working AC and a non working pair ( will not update firmware no matter what I do). What I want to do is attach the good camera/ gimbal and the working RC ( with the older firmware) to the AC see if I might be able to see where problem might be and if nothing else to see if I can put arms into travel mode so I can put in case and send in for repair. Any thoughts?
Thanks,
Chip