HP All-In-One 27-p011 doesn't boot from hard drive or USB.
I’m trying to troubleshoot an older HP all-in-one from around 2015 that will not boot from anything. I have swapped in two different hard drives, removed and reinstalled the CMOS battery, tried USB 2.0 and 3.0 ports, and made bootable USBs with Windows, Arch Linux, and Linux Mint using both Rufus and Balena Etcher. None of the USB drives appear as boot options, and the system will not boot from the hard drive either. I even removed the hard drive completely and tried booting only from USB with no luck. BIOS still opens, but nothing actually boots. I also checked HP’s support page for a BIOS update, but the download appears to have been removed because the machine is old. At this point I’m wondering if this sounds like corrupted BIOS firmware, a motherboard failure, bad RAM, or some HP-specific issue. Has anyone dealt with this before or know any fixes?