I have Iphone 11 pro max. And I need change my battery because my phone’s battery is runnig low.
After I changed my battery the unknown part message is on my phone.
iPhone 11 Pro Max, iOS 16
The wrong battery was installed in the phone. Take the phone back to the shop and get your money back.
Then, take the phone to an Apple Store or authorized Apple Service shop to see if they are willing to install a genuine Apple battery.
They may refuse to do this, because of tampering by unauthorized persons using the wrong part.