Basically, you have to go through the retailer if you're outside China. This is part of how Godox keeps their pricetags lower than the competition. OEM speedlights don't arbitrarily cost twice as much.

In this case, if the seller refuses to help you out, you can try Amazon support or your credit card company, if you paid with a credit card. But if neither of those paths work for you, you're SOL.

It's why we tend to recommend people purchase the Adorama Flashpoint-rebranded versions. Because Adorama is known to support the warranty themselves, and even has their own support website.

Adorama is an Amazon reseller as well.

The Flashpoint versions are identical to Godox-branded units, they're just rebranded so Adorama can easily distinguish theirs from Godox units bought elsewhere, when it comes to offering support.