Even though the Samsung Galaxy Note 7 has — as of Tuesday morning — yet to be officially recalled in the U.S., we now have a slightly better idea of the underlying flaw in the device’s battery that has resulted in dozens of incidents of Note 7s overheating or exploding.

According to Bloomberg, Samsung recently explained to Korean authorities that it needs time to determine the exact cause of the problem, but the company believes the problem occurred during the manufacturing process.

“Initial conclusions indicate an error in production that placed pressure on plates contained within battery cells,” writes Bloomberg. “That in turn brought negative and positive poles into contact, triggering excessive heat.”

There have been at least 35 cases of a Note 7 battery overheating, catching fire, smoking, or exploding. About half of those incidents have occurred in Samsung’s home country of South Korea.

While the company’s Samsung SDI subsidiary had been the primary provider of Note 7 batteries, Reuters reports that Samsung has shifted those duties to China’s Amperex Technology Limited, which had previously made only around 30% of Note 7 batteries for Samsung.

Both Samsung and the U.S. Consumer Product Safety Commission have asked Note 7 owners to power down their devices and not use them.

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