If you signed be prepared for you claim to be refused on the basis that you signed for it.
Don’t be surprised when it happens. Shipping company’s screw customers all the time based on this. like others have already said ALWAYS refuse to accept shipment if there is any damage whatsoever to the box/packing. even if there is no damage to the box or a few minor scuffs damage may not be apparent until you completely unpack and set up the machine.