Failed 2413U

I think my 2413U has failed. I can see it listed in the USB devices but the LED does not light up when plugged in. The interface connection cannnot be established?

[matt (support)]

No LED means it has either malfunctioned or is locked up. Try unplugging it from your Mac and the wall, the press and hold the SET button in while you plug it back into the wall. Continue to hold for 10+ seconds, then release and connect it back to your Mac. Does it then work? If not, then I think it has malfunctioned.