The EliteBook 840 G3 stores the BIOS password on a dedicated chip, but physically removing the Real-Time Clock (RTC) battery can work if the password wasn't written to the TPM chip.
Using another computer or phone, go to a reputable HP BIOS unlocking website (such as bios-pw.org or biosbug.com ). Enter the 5-8 digit code into the website's input field. How To Reset Bios Password Hp Elitebook 840 G3
HP officially ended support for providing these reset files on March 1, 2019 You can still try contacting HP Support The EliteBook 840 G3 stores the BIOS password
This requires opening the laptop, locating the BIOS chip on the motherboard, and using an external programmer (like the ) to flash a clean BIOS image. HP officially ended support for providing these reset
Use an automated hex tool (like the HP Unlocker script found on specialized tech forums) to patch out the password block from your backup bin file.