I'm positive shipping has nothing to do with packing. A lot of people think otherwise.
If there's no outside damage and no inside damage, that's not packing or shipping it's a mater of inspecting a product before it ships.
You have the proof it was damaged, the seller can't prove it wasn't shipped that way.
The seller is responsible for the packing. The shipper is responsible to deliver the package to the buyer's agreed location, in one piece without visible damage.
The transaction is over when the buyer receives his property in the condition he agreed too, NOT the seller. "AS IS" does not mean you get to throw a 65lb amp in a cardboard box with peanuts and say "Good By".
I learned that 10 years ago on EBay. I instruct people how to pack, my equipment. If they say anything that would lead me to believe they wouldn't pack the equipment correctly. I put them and Ebay on notice before they even ship the product. I recommend they take pics as they pack. With no pics it better be a perfect packing job and sent freight strapped to a pallet in a bubble.
Cary pulled that with me. I got the whole 10.5K back. They actually sent the two boxes ground. My FedEx driver knew I would reject it..
I told Cary to take a flying _____ at a rolling donut. Never use ground on expensive equipment. Never, ever, EVER. Cary insisted, so did I..