HP EliteDesk 705 G1won't boot

[kennethl]

I had a fully working HP EliteDesk 705 G1 SFF, except that the PCI video card was noisy, so I thought I would take it out to fix the card's noisy fan by dusting it and adding some oil. In the meantime, I switched the video in the BIOS > Advanced > PCI VGA Configuration to "Internal", shut down the computer, removed the PCI video card, and connected the HDMI cable to the motherboard's HDMI slot then tried to start it back up so I could work on it while I took my time to fix the video card.

Now, it no longer starts up. I push the power button and the 3 lights on the keyboard momentarily flashes, than after 15-30 seconds or so, the CPU fan ramps up to maximum speed. The screen stays black, no other lights are seen on the keyboard. I have to hold down the power button to force it off.

I tried reinstalling the PCI video card & connecting the video cable to it, I tried unplugging all cords from the computer except the video/keyboard, I tried reseating all the RAM, I tried removing all the RAM except for one (in slot 1, then in slot 3), I tried resetting CMOS by holding down the CMOS button for 5+ seconds. I tried connecting the video cable to the motherboard HDMI slot with the video card plugged in, I tried connecting the VGA cable from the motherboard to my monitor, I tried holding down F10 before starting it up, ... after each of those steps, I still get the same symptoms on boot - black screen, loud CPU fan.

How can I fix this issue? I suspect that if I could change the PCI VGA Configuration in BIOS back to Auto or the PCI card, it should boot, but I can't even see or get into BIOS. Thanks in advance.