HP Workstations are increasingly moving away from displaying halt codes. On the ZBook 15 G5, entering the wrong password three times may simply result in a "Shutdown" or a permanent halt without providing a code. This is a security measure.
Be extremely cautious of executable "reset tools" found on forums or YouTube. These are frequently malware vectors. hp zbook 15 g5 bios password reset free
Resetting the BIOS password on a professional machine like the HP ZBook 15 G5 HP Workstations are increasingly moving away from displaying