Never had any trouble returning things with Amazon. You just need to check the "Item is defective or doesn't work" option on why you are returning it. There is no charge for that.
Mine was one of the earlier documented failures, back in June. When I returned it, I made a point of speaking to a human, who eventually filled out a Product Safety Report. It took a while, but I was firm that I felt it was a hazard, and I didn't want it simply to be repackaged and sent back out. Which seems to have been a well-founded concern.
Folks, it's not like Amazon has a rack of basses to test these things, nor a test bench, or even a multimeter. At best, they plug something in, and see if it powers up. Given the pressure the workers are under to meet standard performance metrics, even that is a best-case scenario.