Yes, the CC company will very likely ask detailed questions about what you have done to resolve the issue with the reseller directly. If you have exhausted that route, and can provide evidence from the manufacturer that you were sold illegitimate goods, you should be on solid ground with the CC company.
What I would do: Get confirmation from the manufacturer that the product is not theirs. Go back to the retailer and tell them what you found, and say that if he doesn't issue a refund, you will file with the CC company to reverse the charge. This alone may motivate the seller to just give your money back and avoid the hassle, because the CC company WILL hassle them. They don't want to be out the $400 any more than you do.
It would not hurt to just call the CC company and explain the situation, to get their feedback of steps you should be taking. Each company probably has their own set of policies. I recently did this with AMEX for some unauthorized charges that had appeared on my account - called them up immediately and started a case. They gave me instructions on what they expected from me. I followed the instructions and called them back. A month later my CC balance was credited.
Good luck.