Solution:
If the "Lock Front Panel" option is enabled and a "Front Panel Password" was not enabled then access to the front panel controls is completely denied.
If you cannot access the Perle through the Manager (or the Administrative user password is unknown), then you cannot follow the normal procedure of reseting the unit to factory using the front panel menu.
The 833IS can be rebooted to load the factory default configuration by holding down the Escape and Down Arrow keys while the unit is powering up.
The unit will display 123F..., the "F" represents factory default being used.
The only method to recover an 833RAS is to perform a Service Download of the firmware via the serial port so the unit will be reset to factory default (see link below).
An 833AS flash can be reset only with the newer Systems cards that support the v2.x BIOS. Use the same method as the 833IS above.
833AS's with the older v1.xx BIOS cards cannot be easily recovered. Currently the only method to recover is to send the System Card in for servicing to reset the flash.