When the Galaxy Note 7 recall was confirmed a couple of weeks ago, Samsung said that customers in China were not affected by the recall as the handsets sold there featured a battery from Amperex Technology Limited which is now the primary battery supplier for the Galaxy Note 7. The first reports of a Galaxy Note 7 burning up in China came yesterday which was probably the first such report from the People's Republic. Samsung has conducted an investigation into the incident and found that the handset didn't burn up due to an issue with the battery.
Samsung has posted a statement on its Chinese website clarifying that “the damage to this product was caused by external heating,” without clarifying the method and manner in which this external heat was applied to the device. Battery supplier Amperex Technology Limited sent out its own statement confirming that the unit did have its battery but “according to the burn marks on the sample, we surmise that the source of the heating comes from outside the battery, and it's very likely that there was an external factor causing the heating problem.”
It was important for Samsung to quickly look into these report as the replacement inventory that it's now shipping across the globe features a battery from Amperex Technology Limited. It's now widely believed that the faulty Galaxy Note 7 batteries were supplied by Samsung's own battery-making division, the company is no longer sourcing batteries for its latest flagship from Samsung SDI.
A person reportedly familiar with the matter has claimed that the external heat source was possibly a fan heater or an induction oven. This could mean that the person who claimed their Galaxy Note 7 burned up could have done this intentionally, or they could have left it inside an induction oven for some reason, only you can choose what you wish to believe.