I got my black Teensy 3.1 about a month ago, and it worked pretty well, until yesterday. I plug my Teensy into my PC, but it didn't show up in the Device Manager. There's no COM port nor HID device detected. Then I borrowed my friend's green Teensy 3.1 and plug it into my PC, and his Teensy works just fine. Is there any way to verify whether my Teensy is broken?