MC68HC908GP20 Datasheet, PDF (220/406 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

If the security sequence fails, the device can be reset and brought up in
monitor mode to attempt another entry. After failing the security
sequence, the FLASH mode can also be bulk erased by executing an
erase routine that was downloaded into internal RAM. The bulk erase
operation clears the security code locations so that all eight security
bytes become $00.
Advance Information
220
MC68HC908GP20 — Rev 2.1
Freescale Semiconductor