In a support document, Apple said a "small percentage" of devices manufactured between September 2016 and February 2018 are impacted. Apple will repair iPhone 7 devices, free of charge, if they show symptoms of the issue.
Apple said the issue is caused by a component that has failed on the main logic board.
There are three model numbers (on the back of the iPhone 7) eligible for Apple's repair program:
A1660, A1780 - China
A1660 - Hong Kong, Macao, US
A1779 - Japan
Apple said it will only repair affected iPhone 7 models within two years after the first retail sale of the unit, and the iPhone 7 Plus isn't part of the program. The company added customers who may have paid for a repair related to this issue will be reimbursed.
In 2016, Apple acknowledged in an internal document that some iPhone 7s can fall prey to the bug. Reports from customers said Apple replaced their faulty iPhone 7 with a new one.