because they MAY:
-Deny the claim
-Grant the claim and hold you responsible
-Grant the claim but it is Amazon funded.
If you touch it , it is an automatic loss. You refunded 40%, you have a good chance of winning, if you really want to reply, just tell them you already refunded and charged a restocking fee per policy, otherwise just wait on their decision. You can always appeal if you lose the claim.
ETA: does it say action required under the AZ claim ?