Samsung announces final conclusions regarding the Galaxy Note 7 battery issues
Samsung says that, for the past several months, it investigated all aspects of the Galaxy Note 7, including hardware, software, assembly processes, and so on. About 700 Samsung engineers tested no less than 200,000 Note 7 devices and 30,000 batteries, being able to replicate the incidents that consumers reported last year - overheating batteries and "thermal failures."
Batteries inside the Note 7 were flawed, the phone itself was notto Samsung, the Galaxy Note 7 itself (including its design, hardware, and software) did not contribute to the failure of batteries. Thus, this was a battery-only issue.
We're not going to get too technical about this, but both Note 7 batteries could overheat and catch fire due to a combination of manufacturing and design flaws. In particular, Samsung SDI-made batteries could have failed and short-circuited due to deformations at the upper corners, and thin internal separators, while the problem with Amperex-made batteries lied in missing (or misalignment of) insulation tape and (again) thin internal separators. If you visit the first source link below, you'll find three PDFs at the end of Samsung's press release - you can check out technical details there.
Samsung re-confirmed that, to date, 96% of "about 3 million" Galaxy Note 7 units sold and activated around the world have been recalled.