what do i do??? :(

i really want to get the match made in heaven co op but i cant if one mic doesnt work!!!!!!

You should just be able to push the power button again for it to sync.  When it's flashing green, I believe it means the mic is trying to sync up with your xbox.  Mine does the same thing, and all I do is push the power button again and it syncs up just fine.  Hope that works; if not, then you might be SOL.