iPhone not holding charge? How to replace an iPhone battery
For an iPhone SE, 6, 6 Plus, 6S, 6S Plus, 7, 7 Plus ... send it, have Apple replace the battery, then ship it back to you.
BGR7y
Apple will replace your iPhone 6, 6s, or 7 battery for $29 even if it’s not being throttled
We’ve already told you how to go about replacing the battery of your old iPhone (the full instructions are right here), and it should all be a reasonably painless experience. However ...