Apple recently began offering battery replacements ahead of their intended schedule, after the recent debacle regarding unit slowdowns due to battery life.
Notably, though, the company did not set a threshold as to which batteries and units qualified for the discount. Fortunately, Apple just confirmed that it would replace batteries on older phones (starting from iPhone 6). This will happen regardless of diagnostic test results. This clarification arrives after more rumors came out. In particular, these dealt with rumors regarding refunds for people who paid USD 79 for battery replacements. Of course, Apple will still need to verify certain factors. Specifically, they need to see if the phone has not been damaged some other way. lastly, they will also check if the unit makes use of third-party components.
Apple is still battling the huge dent left on their reputation by the recent issues. Currently, the company focuses on keeping their current consumer base together.