I know, this seems very basic, so basic in fact that it makes almost no sense to mention it. But mention it I must.
New stock received in your business cannot be purchased unless you take it out of the boxes, receive it into your retail management software, price it and place it on display for customers to see.
This is your job to do. Not a supplier. No, your job.
Do it and the new products you have received may sell. On the other hand, if you prefer, leave the product in the boxes and complain to the supplier that their product does not sell.