I bought a razer blackshark v2 x and when i tried to put in the code for the 7.1 surround sound it said that the code is invalid even though i was the one that revealed the code by scratching it wasnt already revealed when i got it.
Be sure, that you have entered correct characters for eg. you could put "0" instead "O", or for eg "I" (capital i) with "l" (small L).
