I found this: https://h30434.www3.hp.com/t5/Notebook-Boot-and-Lockup/enter-administrator-password-HP-compaq-cq40/td-p/4595428
it looks like you can try one of these two passwords: 47498324 or 00586459
according to an HP employee:
1. Use the unlock code posted above to enter the BIOS
2. Disable all passwords that are enabled
3. If asked for current password - type the unlock code
4. For new password, just press ENTER key
5. Repeat the same for verify password column.
6. Then leave the BIOS by saving & exit option to save the changes.