After completing the BIOS update, the PC will not start

[Tabru]

Hi,

me was offered some updates by the HP support software, including a BIOS update.

Everything went perfect. The PC shut down, update started and was checked, all OK. Then the PC rebooted and beeped 8 times. The monitor stays dark.

Then i googled on another PC and tried a start with the Windows + B (V) key. The keyboard does not light either, so keystrokes do not seem to be possible.

Then tried a BIOS update via USB stick. Without success. It seems like the PC is restarting every few minutes.

I have already disconnected the PC from power, removed the battery, memory  and HDD and deleted the CMOS with the jumper.

What else can I do?

[Hiatus]

Did you follow the instructions to the T for the reset?
I'll attach SDH's guide here for you:

Remover the power cord. Disconnect all peripherals such as mouse/keyboard/monitor cables from the backplane, and also the ethernet cable. Remover the motherboard battery. Press the start button. Hold your slightly moist fingertips crossing all three prongs of the power supply cord attachment. Press the little spring loaded CMOS reset button you found on the motherboard and hold 5 seconds. Wait an hour, do all that again. Put back in the battery. Press the CMOS button again and hold in for 5 seconds. Reattach all your peripherals except network cable. Reattach the main power cable. Turn on the workstation.

If you missed a step, try again.

Hiatus