Selling product that is broken, ie. already broken...

Selling product that is broken, ie. already broken when it is on the store shelf.
But still you must not return it, but you must be forced to return it for repair. This is certainly not the case, for example, with Inet, which replaces such a product directly.

Update: When we got the item back after a few weeks of repair, it is still faulty, even though it says that the fault has been rectified and that the product has been tested afterwards.