A manufacturer's defect is certainly a possibility. Manufacturer's have to accept a certain failure rate, otherwise it becomes prohibitively expensive to produce goods. Warranties are often legislated to protect both the consumer (to ensure that manufacturers take responsibility for defects) and manufacturers (to keep costs down by permitting acceptable failure rates). None of this implies that the manufacturing is shoddy. It simply accepts that it is impossible to guarantee that every unit comes off the assembly line perfect and prohibitively expensive to do comprehensive testing on every unit to lower failure rates to near-zero.

Based upon reports around here, your situation sounds exceptionally rare and acceptable. Yes, it is frustrating to you as a consumer -- but that's why you have recourse. Quite frankly, I'd be more concerned about the "format errors" that people are seeing. The failure rates are much higher and implies some sort of systematic problem with manufacturing or the firmware.

Yet I wouldn't discount a return either. Some people will return a product in pristine condition (e.g. wipe it down prior to returning it and leave protective plastic in place until they know they're going to keep it). It isn't exactly unheard of for consumers or stores to replace seals either.

To make a long store short, no one here knows the history of your unit so it's hard to make reliable assumptions about accountability. We only know that you've received a defective unit that needs a replacement, and that Chapters or Kobo needs to do so in a prompt manner.