HP 510-a010 Press the ESC key for Startup Menu

[CroSoft]

ESC key, Bios and OS are ALL inaccessible. Only displays "Press the ESC key for Startup Menu" with or without the HDD connected. Only the wired USB keyboard and mouse, AC power and VGA monitor are connected.

HDD has contents and is available via USB/SATA external and my functioning Dell laptop.....

This HP 510-a010  desktop pc is a client pc that I'm trying to resurrect.....

Any new insights from you are appreciated!

CroSoft

[itsmyname]

@CroSoft -- after you press the ESC key, does a menu display? Does one of the options on that menu allow you to enter BIOS SETUP ?

[CroSoft]

No menus or operational selections and the USB keyboard or mouse are useless, 

Power off is the option. Going to try to find a new motherboard.

[itsmyname]

@CroSoft -- is this your computer: HP Pavilion Desktop - 510-a010 (ENERGY STAR) PC Product Specifications | HP® Customer Support

It dates from 2016.  It may be difficult to find a "genuine" HP motherboard.

This page describes your motherboard: HP Desktop PCs - motherboard specifications, Iris-A8 | HP® Customer Support

Note that this computer has an external power-supply. So, you are limited as to what a replacement motherboard must have.

With the computer powered-off, have you tried repeatedly tapping the ESC key, and continuing to tap it while pressing (once) the on/off button?  Maybe, one of those taps of ESC will be accepted by the motherboard.

Maybe, try a different keyboard.

Definitely, try connecting your keyboard to a different USB port.

Note that with a new non-HP motherboard, you may be required to purchase a new license for Windows 10, adding to your cost.

My recommendation is to buy a brand-new computer that is advertised as "ready for Windows 11". It will have Windows 10 preinstalled, which you can use until October 2025, and you can take the free upgrade to Windows 11 at any time in the future.

Or, near me, there is an "owner/operator" computer store, who sells refurbished computers, running Windows 10, for less than $100 (USA).  If your computing needs are "modest", this will be an option for you.