I would sign up for email updates for the tracking number on usps.com
and file a missing mail claim on usps.com too. If it doesn't deliver,
you will be refunded.
Get on the phone with eBay and/or your bank ASAP. A phone call would
resolve this. Now that it is 5 months later, I think going to your bank
again is the best route.
You can take photos and escalate the claim to eBay. However, it is
unlikely you will win. They usually close in the buyer's favor. I would
refund the buyer, then file an appeal. I haven't had that scenario in
awhile (late 2019 was last time), but eBa...
