Have you tried hot plugging them with it already on? Power it up without the keyboard and Mouse. Then hot plug them one at a time and see if it will suggest a proper new driver for them to download? Or auto set proper new configurations for them? Sometimes it has to see them as “new devices” being plugged in hot to do this.
That’s a thought. The computer may have only been hibernated when I tried firing it up and then hot plugging the keyboard and mouse in.
No luck.
Looking in Device Manager>Universal Serial Bus controllers, the pertinent hubs listed all have (under Properties>Power Management) “Allow this device to wake the computer” turned off AND GRAYED OUT, regardless of whether “Allow the computer to turn off this device to save power” is checked or not.
I suspect therein lies the problem, but I have no clue how to approach it.
Possibly this is a BIOS setting problem?
AHA!
I had to go into the BIOS Power Management Settings, but, that did the trick.
This machine is so quick, I had to try the “boot and hit F2 repeatedly” command 3 times before it “caught” and went into BIOS / UEFI menu.