No official procedures from HP worked, this is the only procedure which worked for me after my HP ProBook 4320s got bricked from BIOS update. Thanks to aularon for his post here which help me with the solution.
Behavior: after turn on screen is black, caps lock is blinking slowly and Wifi LED is solid orange
Fix (modified to Windows world):
- Download Rufus utility and format 4GB USB drive to FAT (not FAT32, but pure FAT) file system including FreeDOS system files.
- Create directory HEWLETT-PACKARD/BIOS/CURRENT on this flash drive
- Download BIOS file from HP, extract exe file and also extract rom.cab which is inside this downloaded exe file.
- Copy Rom.bin and efibios.sig (not rom.sig !!!) to folder HEWLETT-PACKARD/BIOS/CURRENT on flash drive. Rename these files to 68AHH.bin and 68AHH.sig
- Plug battery and AC, Press Windows+B buttons, push power button for few seconds till caps lock start blinking, wait till flash drive led starts blinking, release Windows+B, and wait…
- Now important part – it looks it is doing nothing, but it should start doing things within 30s (booting off and on). Just wait on it and should turn off completely (for more than 30s). Remove the flash drive and boot. It should boot to bios now!