Chosen Solution
I installed an ifixit battery in my XS Max, but the Battery Health still says “Service”. How do I fix that? Thanks
Check the listing for the XS battery… The Battery Health feature released in iOS 11.3 (March 2018) is compatible with our battery. So verify and insure you have the latest iOS release installed on your device. Otherwise, please contact iFixit support.
This has intentionally been done by Apple so that you will lose trust in independent repair. The battery itself is fine, and will work fine. https://www.ifixit.com/News/apple-is-loc…