For the most reliable results, always have your battery replaced at an Authorized Apple Service Provider or an Apple Store to ensure the serial number is correctly registered to your device's logic board. Check Coverage - Apple
Until then, checking that hidden serial number is the best detective work you can do yourself. apple battery serial number check
A common scenario involves a user replacing an iPhone battery independently. Post-replacement, the user observes a "Service" message in Settings. For the most reliable results, always have your