Up2Stream 2.1 amp board usb connection

Currently I am using an up2stream 2.1 amp board, connected to two bookshelves composed of an old tweeter and a dayton tcp115 woofer and a 12" subwoofer.
Everything is working great and as supposed on only 60w of power (12v, 5a) and gets pretty loud without any distorsion.
The question I am having is, can this board be powered on and off by the usb connection?
Some time back it happened and I was pretty amazed of it. But somehow it is now happening anymore. Any idea why? Should I try a reset maybe it will work again? Or how can I enable again the feature?