HP Pavilion 15 CC-749TX does not boot up, capslock gives 5 long 3 short blinks

[Ivan_AU]

Suddenly my laptop HP Pavilion 15 stopped to boot up. Nothing on display. The CapsLock ley light gives 5 long and 3 short blinks. I suspect that BIOS was corrupted. I tried to disconnect battery and keep the power button pressed for 15 seconds to reset BIOS. This did not help. I tried to keep Win+B keys before and after pressing power button. This did not help either.
I tried to resit M.2 hard drive and RAM modules. It did not help either. Actually even without RAM modules powering gives the same 5 long and 3 short blinks.

Are there any other specific procedures to restore BIOS. Any suggestions are appreciated.

[banhien]

@Ivan_AU 

Please try a hard reset and see if it works.

•    Power off your notebook,
•    Remove the a/c adapter, battery and everything that is attached to your notebook,
•    Hold the 'POWER' button down on your notebook for about 10 seconds,
•    Plug in the a/c power supply (without battery) and power on.

Regards.

[Ivan_AU]

I have tried that, as well as the USB firmware update option with Win+B holding key before and after the laptop powering. None of the options helped.

[banhien]

@Ivan_AU 

Perform a CLEAN install would be a option now.

For (original) Windows 10/11. please use Cloud Recovery tools

    https://support.hp.com/us-en/document/ish_4511095-4511141-16

Regards.

[Ivan_AU]

From what I read 5 long 3 short blinks means that controller can't reach bios, therefore nothing is loaded to make possible to choose boot options on screen to select Cloud Recovery USB drive.
It looks like BIOS is either busted or corrupted. Unfortunately, the option with BIOS update through USB did not work. Internet suggest to press Win-B combination while turning on Power, and keep Win-B pressing for another 45-60 seconds after releasing Power button. There are also some suggestion that some HP model require to press Win-V, or just V, or just B instead.
The available HP documentation on this model does not provide any explicit instructions what combination of keys to be used for BIOS restore or update. I would like to know it exactly, so to know if all my options to restore the notebook without hardware replacement are exhausted.