Playing devils advocate here but… I suspect what is happening here is a previous purchaser bought it (broke it?), returned it under a different reason (eg. I dint like it) and Amazon decided it is not worth the hassle of rechecking every return labeled as such.
Mind you this is no consolation for someone like you who has go to through this return process, but I cant believe Amazon is “winning” by keeping a defective product like this in rotation long enough for someone to “eat the cost”. Defective products hurt Amazon as well and I’m sure they’d rather take the hit if they could pin point which products are defective.
You could argue that they should bear the cost of validating every return, but clearly someone has crunched the numbers and the program is likely not cost effective.