Three months after its largest-ever recall, Samsung has finally completed its investigation of the Galaxy Note 7 fiasco. The high-profile flagship phone was recalled (twice) and cancelled after reports of explosions and fires, and now Samsung thinks it has finally nailed down the issue.

Samsung’s verdict: two separate battery construction issues were to blame. Samsung Electronics used two separate suppliers for the Galaxy Note 7—Samsung SDI, a sister company in Samsung Group, and Amperex Technology Ltd (ATL)—and it turns out both manufacturers had their own issues. Given that Samsung’s first recall and attempted fix didn’t work, it’s no surprise that the problem behind the Galaxy Note 7 is a complicated one.