Razer Blackshark V2 x microphone doesn't work on PC

Hello, I might be able to help you, try everything below.
Maybe you have the microphone on mute.
Also check windows microphone settings that you may have it disabled on specific apps or all the apps.
You can also check the windows input microphone settings that is letting you choose what mic you use.
Also go to Sound Control Panel → Recording → choose the microphone if you see it and select it → general on the bottom you have Device usage put it on Use this device (enable) after this also try → Levels and put microphone volume to MAX and Microphone boost +20.0 dB (this are my settings).
Did you make sure the headset cables were connected properly?
If did so then did you try to move to the back & front of the case the connection of the cable?
The problem might also be hardware drivers issues so try updating them.

If the problem still persists might be headset internal damage due delivery so try to return them and get another pair of headsets. 

I hope I was helpful!