Apple has finally identified what causes the unexpected shutdown of the Apple iPhone 6s devices and it's apparently a battery problem. Although not all Apple iPhone 6s suffer this problem, only the devices manufactured in September and October 2015 were the one's affected and thus were the only ones covered by the program.

For consumers experiencing unexpected iPhone 6s shutdowns, they are advised to visit an Apple Store or any Apple Authorized Service Provider. They can also contact Apple Online to have the device's serial numbers checked to determine if it is eligible for a free battery replacement because only limited serial numbers were affected, MacRumors reported.

Although Apple offered a free battery replacement for iPhone 6s, note that other problems that could prevent the battery replacement such as cracked screen must be repaired first for a fee before replacing the battery.   

However, if the owner of an affected iPhone 6s has already paid for the battery replacement previously can contact Apple for a refund.

The company explains that the recent problem with the iPhone 6s is not the same with the problem faced by Samsung as it is not safety related issue. Though Apple didn't tell how they came to a conclusion that the battery is the problem.

Apple began investigating the issues after many users were reportedly complaining their iPhone 6s powering down to 50 and 60 percent of battery remaining at room temperature or below according to Apple Insider.

It is also reported that iPhone 6 Plus and iPhone 6 is affected by the so-called "touch disease" where some of the phones have reduced touch sensitivity or have developed a flickering gray bands which may be due to the bending of the device which causes the touch controller to come loose, Apple Insider reported.