Samsung has concluded that two separate battery issues were to blame for the faults with the Galaxy Note 7, according to a report.

The South Korean giant is set to reveal what exactly went wrong with the device at an event on 23 January, but the Wall Street Journal claims to have got its hands on the inside information early, citing “people familiar with the matter.”

Its sources say that Samsung used three independent quality-control and supply chain analysis firms to conduct its investigation.

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The first issue has been traced back to the batteries manufactured by Samsung subsidiary Samsung SDI, which didn’t fit the phone properly, causing the handset to overheat and, in some cases, catch fire.

Samsung reacted to the first wave of explosion reports by expanding production of Note 7s equipped with batteries made by Hong Kong firm Amperex Technology.

However, the increased pressure on Amperex Technology led to unspecified “manufacturing issues”.

Samsung is keen to draw a line under the fiasco before unveiling the Galaxy S8 and S8 Edge, its highly anticipated new generation of flagship smartphones.