Empty box scam A-Z appeal lost, now have proof of scam

I will try to be as brief as possible.

1. I sold a high value item which was FBM and the customer claimed they received an empty box. The item is not only high value, but also HAZMAT and large and heavy. There was no question the item was delivered as expected and was also confirmed by the courier.
2. I provided proof of delivery to the customer and asked for further evidence of the “empty box”.
3. Instead of responding to my request for evidence/more information, the customer filed and A-Z claim citing “Item not received”. The A-Z claim was granted and I was given the option to appeal.
4. On appeal, Amazon sent an email asking for more information, specifically proof of delivery, tracking info, etc. I supplied the requested information on the same date it was requested and updated the appeal form stating the same.
5. Four days later Amazon sent a duplicate email asking me for further information; proof of delivery, tracking information, etc. I attempted to supply the information and update the appeals form, but was unable as the option to submit/upload was unavailable/greyed out.
6. A few days later Amazon sent an email stating the appeal was declined and the A-Z claim desion to refund the customer was upheld. The reason cited was that I did not supply the information requested in the duplicate request.
7. I immediately contacted seller support and created a case and attempted to explain the situation that I was unable to submit the proof twice and Amazon seemed to have overelooked my first submission. The case was transferred to A-Z team. No response from the A-Z in several weeks.
8. Since then the customer has sent further messages asking for a refund stating that the product they received had a fault. I asked the customer for photos showing the fault, and the customer has provided photos of the product that they said they never received and subsrquently already received an A-Z refund for.
   9 The customer continues to message me with further claims of damages/faults/etc in an attempt to obtain a furthr refund.
9. I have contacted seller support many times about this and the representatives can clearly see the message history and he photos of the item the customer initally claimed they never received, and they agree this appears to be a scam. They say all they can do is transfer to A-Z team.

A-Z team have responded and stated that whilst they understand my position, the appeal is denied and there will be no further response in this case.

Is there anything at all I can do about this?

I am a fairly new seller and this clim has defect my account and I can no longer sell as I have zero chance of winning the buy box.