A cover for mounting to a Universal Serial Bus (USB) electronic device, the USB electronic device includes a shell defining an opening and a USB connector exposed at the opening. The USB connector includes a GND pin and an ID pin. The cover includes a main body and an elastomeric push button; the main body engagably attaches to the shell and covers the opening; the elastomeric push button is formed on the main body and is configured for powering on or off the USB electronic device; the elastomeric push button includes two metal pins connected with each other and configured for short-circuiting the GND pin to the ID pin when the elastomeric push button is depressed.