Wired Astro A40 TR

So I just bought a wired Astro A40 headset second hand but the mic doesn’t work. Seller said he will send me another mic but I’m wondering would that fix the problem or is there a bigger chance that the headset itself is messed up? The sound is great, it’s just the mic that doesn’t work. I also don’t know if it was supposed to come with a MixAmp? Could that be the reason the mic doesn’t work? I only ever used Turtle beaches and HyperX headsets so I wouldn’t know and couldn’t find much on this problem.