New Canon 5DM3 or tampered with?

I'm guessing you are in the US and the laws are perhaps different there compared to here.  In Australia you would have no problem with the warranty.  Here the seller/retailer is bound by law to provide you with goods that are of merchantable quality and suitable for the purpose they were sold for regardless of whether it was a product sourced from the local company or imported.  If they are not, then the seller must remedy the situation.