Desktop Boot and Lockup

 Last week I updated the BIOS on my HP EliteDesk 705 G3 Microtower PC using the option within the BIOS. 

The latest version of the BIOS (version 02.41, released 8 Nov 2022) was automatically downloaded, and a screen was displayed saying the update had been successful and the PC would reboot to complete the process. All good up to that point...

However when the PC rebooted, the PC had no display output and the USB ports no longer worked.

The motherboard has power to it, the CPU fan spins and the ethernet port lights when a cable is attached, but that appears to be it. There weren't any beep codes.

I've tried both the DP or VGA outputs from the graphics card (which had been working fine up to the BIOS update) but there's no output from either port. I also tried the onboard VGA after removing the graphics card but there's no output from it either.

Unfortunately the PC is out of warranty. I'd normally not update the BIOS on a working PC but the BIOS update was flagged as fixing security issues.

HP Support offered some initial troubleshooting help but we couldn't resolve the issue so they tell me this has been escalated to HP's Customer Relationship Team. I'm waiting to hear back from them.

Has anyone else run into problems with updating the BIOS on their EliteDesk PC?

If so were you able to find a way to fix it?

I've tried resetting the CMOS and recovering the BIOS but neither has worked.

Thanks in advance.