Greetings,
Welcome to the forum.
I am not an HP employee.
Eight beeps means "Invalid ROM image detected". The MB could be DOA. This means none of the following suggestions will work. Time to replace the MB or purchase a new HP PC.
You tried a BIOS Recovery (link). This failed.
Other possible recovery options:
-Booting to USB BIOS Recovery may be available before looking at a MB replacement.This procedure can be reviewed at this HP site (link). BIOS update sp67068 (download) is the latest BIOS update for your PC.
Look in "Update the BIOS when Windows does not start".
-You could also remove the CR3032 MB battery to reset CMOS. Let the PC sit for about 10 minutes. Replace or install a new battery.
-Or try MB jumper setting to clear CMOS (link).
Regards