The HP EliteBook 840 G8 is a business-class laptop with Intel 11th-gen CPUs. It uses an advanced security chip (TPM 2.0) and HP’s Sure Start (self-healing BIOS). Traditional "CMOS battery removal" on this model.
reset the BIOS password; the data is stored in non-volatile memory that does not require power. Backdoor Passwords hp elitebook 840 g8 bios password reset