One of the most important things to remember in a situation like this is...DO NOT try to fix it yourself before you talk to the vendor. If you try to fix it and it doesn't work, the vendor may deny you a refund or exchange. This isn't a matter or the vendor being a dick, it's just a matter of the vendor not being able to know what really happened because you've now changed the condition of the blade. I fell into this situation once when I received a yanagiba that had a rust spot on the back side of the blade. I figured I'd try to fix it myself first, but discovered that the rust had actually pitted the blade. The vendor honored the return, but asked me to contact them first if anything like that happened in the future. Where as you might be thinking "I know what I'm doing, there's no reason for the vendor to have a problem with this", the vendor (who may deal with hundreds of customers a day) is thinking "now I've no way of knowing what condition the blade actually showed up in". Make the phone call, it'll make life easier for everybody. I hope this makes sense.
Be well,
Mikey