avic d1 d2 nav disc is locked in unit

my stupid pioneer rep showed us that we can "lock" the nav disc in the unit so that no one can steal it. all you had to do was hold down a couple of buttons. so now when u hold down the open button it folds down to expose the drive but the eject button does nothing.
well now 2 years later ive sold the unit and the customer needs to be able to switch disks. pioneer tells me that they dont give out that info, and that i need to contact my rep. well as most reps dont keep there jobs for more than a couple years hes not reachable.

so does anyone know how to "unlock" it? pleeeeese

(p.s. this is a retarded feature that can only cause problems, like a security code!)

avicd2 -  hold av & info, press reset, then release when turns on