Poor design and userbility is still a failure
Surely if a DVD player still "doesn't work" after 20 minutes fiddling then it should be returned as malfunctioning. Just because the hardware isn't broken doesn't mean that it's actually fit for purpose.
Good user interface design is key as to whether your product is a success or a failure.
If a manufacturer is getting a high rate of returns even though the hardware is still working, it suggests that they need to look at how userable their product really is!