What the ship just happened?

I believe @akg_ca covered how best to protect yourself. Wait until the object of your desire is offered with OEM packaging and offer to pay for double boxing. "Fragile," This End Up," and "Heavy" stickers help as will adequate insurance. "Signature required" helps but only if you catch him first before he drops it on the porch.

If it makes you feel any better we've all likely had this happen. When I lived in S. Florida, I bought a turntable which UPS promptly left on an unprotected porch during a 6 hour rain. Drenched was an understatement and nothing was the seller's fault; it was all on UPS.

I always request the seller use Fed ex and then I have the package delivered to my nearest Fed ex store, this way when I go to pick it up I have the Fed ex employee open the box and we both check the contents for damage and if any damage is found I refuse delivery of the package. This way there can be no doubt about when or where the damage occurred, I have never had any problems with this method of delivery, and it assures that everyone's bases are covered.

One BIG no no is never just wrap a big amp(or any heavy piece of equipment) in just bubble wrap. The first time it’s dropped all the bubble wrap pops and your protection is gone.
I worked at an audio company for many years where we’d get in units to be repaired. We’d go through great pains to describe how to pack equipment when sending it in. Use hard foam insulation cut to brace the unit and double box it. There was always someone that didn’t want to go through the work and cost of doing it right and would bubble wrap an 80 or 100 pound amplifier and stuff it in a barely adequate box. The first time UPS or FedX drops it all the bubble wrap pops and it’s down hill from there. We’d get the box with the face plate or binding posts sticking through the side of the box all bent up. The delivery companies will many times claim insufficient packing and not want to pay for damages. The customer would almost be in tears when you tell them it will takes several hundred dollars to repair the shipping damage little lone what they sent it in for. And the chassis will never look the same.
We’ve actually had customers say they saw the FedX or UPS truck pull up to they’re house and roll a 100 pound amp box off the back of the truck dropping it all the way to the ground. The customers response was to decline delivery in most cases.

I bought an old Mac MR 78 and wanted it tuned up at Audio Classics by Modaferri.

First, I paid up for an OEM box which was shipped to me.  Don't remember exactly, but cost maybe $75? at the time.

Next I shipped UPS insured.  It arrived there with the glass face plate broken.  An expensive replacement, I was relieved that the insurance covered it.

Although the whole process was expensive, I was happy to avoid an even more costly experience, and happy to have my tuner back in tip top shape.

That’s called OPJ packaging.

OPJ stands for Other People’s Junk. My answer to this situation would be simply return with refund including shipping.