To add to this... Bitmain will NOT warranty a device that was not purchased directly from Bitmain or an authorized reseller (but they won't provide a list of authorized resellers, as far as I can see). This policy is not made clear anywhere that I have seen, but Bitmain expects retail vendors (re-sellers) to take returns and then pursue warranty service with the re-seller rather than individual buyers. Also, Bitmain will tell you to do a credit card chargeback if the vendor will not handle an RMA for you, regardless of whether or not they ever claimed they would.
They won't necessarily accept returns directly from someone who isn't their customer, as its possible for people to cause problems. For example if a user sends an S5 to Bitmain, but they purchased from a reseller. Bitmain says they will refund the item, the reseller says "nope" and ignores everyone.
Tldr if you're purchasing from a regional reseller, contact them if someone goes wrong with that sale. It becomes far too complicated when trying to make it a 3 way transaction.
