Fitbit says woman's tracker didn't explode on its own

— -- Fitbit has disputed a Wisconsin woman's claim that her Fitbit tracker exploded on its own.

Dina Mitchell said she had owned her Fitbit Flex 2 for about two weeks, when earlier this month, the fitness tracking device allegedly caught fire on her arm while she was reading a book. She said she suffered second-degree burns on her arm after her Fitbit tracker exploded.

But following an investigation, San Francisco-based Fitbit says the fitness tracker did not malfunction.

"Based on our initial investigation, including testing of her device by a leading third-party failure analysis firm, we have concluded that Ms. Mitchell's Fitbit Flex 2 did not malfunction," a Fitbit spokesperson told ABC News. "The testing shows that external forces caused the damage to the device."

The spokesperson continued, "We have not received any other complaints of this nature and we want to assure our customers that they can continue to enjoy their Flex 2 and all Fitbit products with confidence."

Mitchell had told ABC News in an emailed statement last Sunday, "I was literally just sitting and reading when my Fitbit exploded. It was either defective or really mad I was sitting still so long ... I don't know. Either way, it burned the heck out of my arm."

She said she ripped the device off of her arm as it was still burning and tossed it onto the floor. Mitchell said her doctor had to pick pieces of plastic and rubber out of her arm after the incident.

An emergency care provider in the Milwaukee, Wisconsin, area told ABC News affiliate KTRK that Mitchell was treated the day after she said the incident occurred.

Mitchell, who said she got the tracker as a birthday gift, said Fitbit offered her a free replacement device after she notified the company about the apparent malfunction.