If the method above doesn't work, another approach is to use a master password.
: While this resets the system clock and some settings, it will not remove the BIOS password on the EliteBook 840 G3 How To Reset Bios Password Hp Elitebook 840 G3
When prompted for the password, enter any incorrect password three times. If the method above doesn't work, another approach
This is the first method you should try. When you fail to enter the BIOS password three times, the screen typically displays a or a Product Name + Serial Number + UUID . When you fail to enter the BIOS password
If they provide an SMC file, copy it to the root of a FAT32-formatted USB drive. Insert the USB, then hold Windows Key + Up Arrow + Down Arrow while powering on the laptop to trigger the reset process.
Restart your laptop and enter the generated key in the password prompt. Method 3: Contact HP Support for an SMC.bin File