Minor disaster

[MR ZenWiz]

I just came home from fumigation exile and tried to reboot my main desktop.

It comes up as far as displaying the mobo emblem and stops there - no
keyboard input (wired usb), except I can ctl-alt-del to restart again.
It won't go into the bios, so I can't even boot a live usb.

I vaguely recall seeing this before, but it's been way too long for me
to recall,

Any suggestions or pointers ASAP would be superb.

TIA

MRZ