Don't panic, the 70% final payment you have now is the biggest bargaining chip, so don't pay it easily.
What needs to be done now is to solidify the evidence immediately and issue an official notice to the factory. Don't just say it verbally on WeChat, send an email and use a written "quality objection notice".
Take high-definition videos and detailed photos, especially the wrong color of the sutures, loose parts, and completely different packaging from the confirmation samples. Different packaging is a serious problem. It belongs to "the goods are not the right version", not just a flaw.
Place the 200 problematic products together with the confirmation samples and take photos, and mark each problematic point clearly.
The email states the order number, arrival date, random inspection status, defect ratio (200/1000, 20%), specific non-conformities, and attaches evidence.
Tell the other party clearly: "We will suspend payment of 70% of the remaining balance and negotiate the loan after the quality problem is resolved." This step will put the legal "timely notification obligation" in place, and I will not be afraid of even going to court in the future.
If you ask the supplier to return the full amount, it is often the most unrealistic solution. Suppliers will argue with "you have received the goods" and "some of the products you received can still be used", and finally drag you to death. You now need to calculate all your actual losses, including the value of the product, labor and material costs for replacing packaging, and delay losses.
After calculating the loss, you can choose to have the factory discount the entire shipment, or have the factory replenish and compensate for part of the loss. If you can't agree, you can go through the legal channel.