HP EliteBook 840 G8: Caps Lock Blinking Code 5, BIOS Recovery Fails

[JP989]

Our HP EliteBook 840 G8 is failing to boot after a recent automatic BIOS update. Upon power-on, the screen remains black, and the Caps Lock LED flashes five (5) times (5 long blinks), indicating a BIOS Authentication Failure (HP Sure Start). We have attempted the following standard recovery procedures repeatedly without success:

1. Hard Reset: Disconnected AC, held power for 30 seconds.

2. Key Combination Recovery: Pressed Win + B while powering on with a verified USB drive containing the latest/previous BIOS .bin file.

The system enters a recovery state (fan spins high, USB light flashes) but ultimately returns the same 5-blink error. We need the exact steps for forcing a BIOS recovery specifically on the G8 Commercial Notebook series when the standard Win + B recovery fails, and want to know if this failure points to a corrupt HP Sure Start (CSME) partition requiring specialized tools.

[TzortzisG · Accepted solution]

Hello JP989.

The G8s are too modern a system for BIOS recovery to usually work. According to your post you've already tried the suggested method to reflash the UEFI firmware. There really isn't some kind of "HP employee only" protocol about force-recovery on HP laptops. What most users -actually all of us- do is externally flash the BIOS chip with a good working firmware.

Further reading: https://h30434.www3.hp.com/t5/Notebook-Boot-and-Lockup/250-g6-2sx51ea-2sx61ea-bios-uefi-corrupted-wi....

https://h30434.www3.hp.com/t5/Business-Notebooks/Elitebook-840-G6-Blink-Codes-after-Update/m-p/95382....