I recently bought two lilypads USB, one works perfectly (it's recognized in my computer, but the other one it's never recognized, I even try in different computers and the same scenario with both devices)
So I think that maybe the second one doesn't have a bootloader installed. So I'm triying to "burn" a new bootloader. I have been triying following the guide on https://www.arduino.cc/en/Tutorial/ArduinoISP using as programmer an Arduino UNO but without luck. I ever get avrdude: Device signature = 0x000000 (retrying). Thanks for the help!