Hi

Welcome to Microsoft community.

Given the extensive troubleshooting steps you've already attempted without success, it sounds like the BIOS update process may have failed in a way that has left the BIOS in a corrupt state. This situation is particularly challenging because the BIOS is essential for your computer to initialize hardware and boot any form of software, including recovery tools.

Here are a few additional suggestions, although it seems you might have tried some of these. If all else fails, the solution might unfortunately involve professional repair or replacement of the motherboard.

HP BIOS Recovery

HP computers often include a feature for recovering the BIOS. You mentioned trying many solutions, but just in case, here's the specific process for an HP desktop:

1. Power off your computer.
2. Press and hold the Windows key and the B key at the same time while pressing the computer's power button.
3. After a second, release the power button but keep holding the Windows and B keys until you hear beeping sounds or see the HP BIOS Update screen.
4. Follow the on-screen instructions to recover the BIOS.

If your model supports it, this could potentially restore the BIOS using a built-in recovery partition.

External BIOS Recovery Using a USB Flash Drive

Some HP models might support recovering the BIOS with a USB flash drive:

1. On another computer, format a USB flash drive to FAT32.
2. Visit the HP support website, find the BIOS for your model, and download it.
3. Look for a BIOS recovery file in the downloaded package (this might require extracting the downloaded file). Instructions on HP's website should detail how to prepare the flash drive.
4. With the computer off, insert the USB drive, and then attempt to boot the computer while pressing the BIOS recovery key combination (varies by model, but Windows + B or V are common).

Contact HP Support

At this point, if the computer still does not boot or allow BIOS access, it's likely that professional help is needed. Contact HP Customer Support for assistance. They might offer a repair service or provide further instructions specific to your model that aren't publicly documented.

Professional Computer Repair Service

If HP support is unable to assist or if the cost is prohibitive, a local computer repair service with experience in motherboard or BIOS issues could be your next best option. They might have tools or methods not generally available to consumers that can recover the motherboard without full replacement.

Consider the Warranty

If your HP desktop is still under warranty, be sure to discuss warranty coverage with HP or the seller. A failed BIOS update, especially one initiated by the system's own update tools, should be covered under most warranties.

Unfortunately, a failed BIOS update can result in a "bricked" motherboard, where replacement is the only viable option. However, exploring BIOS recovery options through HP support or a professional service is worthwhile before considering more drastic measures.

Please feel free to let me know how it goes. 

Best regards

Derrick Qian | Microsoft Community Support Specialist