Here’s an interesting, slightly skeptical but practical review you could use or adapt for the topic:
A BIOS password on an HP EliteBook 840 G6 protects system firmware settings and can block booting or access to BIOS configuration. When an authorized user forgets or needs to remove a BIOS password, HP and technicians use specific procedures and utilities to reset it. This essay explains what a BIOS password is, why it matters, the typical reset approaches for the EliteBook 840 G6, how HP’s reset utilities work in practice, security and ethical considerations, and recommended best practices. hp elitebook 840 g6 bios password reset utility work
Removing the coin-cell battery or performing a hard reset will clear the BIOS password on this model, as it is stored in non-volatile memory. Brute Force (BCU) Very Low HP EliteBook 840 G6 BIOS password reset utility