Apple is now offering to replace batteries for the iPhone 6S, if users find that their devices are abruptly shutting down. This is its second global repair offer, just days after the last one for the iPhone 6 Plus's screen issue. "Apple has determined that a very small number of iPhone 6S devices may unexpectedly shut down. This is not a safety issue and only affects devices within a limited serial number range that were manufactured between September and October 2015," Apple said in a statement.