Is there a signature proof of delivery?
Since you are not even located in the US and you are purchasing expensive items and having them shipped to an address of a 3rd party warehouse, there is nothing you can do.
As you were supposed to receive and inspect the goods.
Unless you have a trusted person who will personally take care of signing the packages for you and keeping the deliveries in their hands, you will have no means to prove that the items were not received.
If the tracking shows delivery to the correct address and you don’t live at the address or have someone to handle deliveries for you, it’s your word against their word.
The seller fulfilled his obligation of delivering to your address.
If you need a trustworthy person to receive and sign for your expensive deliveries in the US, I recommend @Mirabella. Reach out to her. Here is her thread: