Generally sellers make the agreed return within 1-3 days after the publication of the review.
During the holiday season in China, this period can be extended.
You can only return the products if the seller disappears or does not answer for a long period of time.
You cannot return products once you have received a refund from the seller
You cannot return the product if it is malfunctioning.
You should first contact the seller to let them know that the product they have sold is not working properly and they will send you a new unit.
Even if the product does not work and the seller does not want to send you a new unit. You must honour the part of the deal and make the agreed revision in the agreed way.
The return of defective products is not allowed in any way.