Turn on the power while continuing to hold those keys down for roughly 5 seconds.
This is the most common hardware-based method. It involves opening the laptop, locating the BIOS chip on the motherboard, using a specialized device (called an SPI programmer, like the CH341A or RT809H) to read the contents of the BIOS chip, and then modifying the file to remove the password. Tools like RCUnlocker are designed to automatically analyze a BIOS dump file and generate an unlocked version for many supported HP EliteBook models. hp elitebook 850 g8 bios password reset upd
Use a hex editor (HxD) to locate the NVRAM region containing the password. Search for HPQOEMSLIC or look for UPD strings. Replace the block with FF values in the password offset. Turn on the power while continuing to hold