Samsung is due to report on the finding of their investigation into their Galaxy Note 7 recall on Monday. Leaks allege that the fires were the result of two separate problems: one manufacturer's battery didn't quite fit into the device, and the other manufacturer's battery had a manufacturing flaw.
http://www.notebookcheck.net/Samsung-Note-7-was-afflicted-by-two-separate-issues-report.192320.0.html