Actually DC it is helpful, serving to maybe confirm my suspicion that my cable is on the fritz.

When I just plug the USB into the laptop, the red light indeed goes on, but only for a second and then goes dark. I think all these cheapo cables must be very similar, so I'm thinking the fact my red light goes off must indicate some malfunction in the cable itself.

And you found I think the EXACT cable I am dealing with since the logo looks exactly the same. I think I even remember the packaging !

Hmmm. Just checked the Sanoxy cable on Amazon you cited and found this:

"The MIDI Cable can support WIN10, but must use in USB 2.0 port, ("NOT FOR USB 3.0 PORTS)"

My Dell laptop is USB 3.0- that would explain why the cable isn't working and the red light goes off.

So, at long last, the cable is good and mystery solved. Just requires USB 2.0.

Geesh !