Why my phone turn off but the battrery still full
Why my phone suddenly turn off, but the battery still full
Why my phone suddenly turn off, but the battery still full
You need a computer and follow the Related Article
If your iOS or iPadOS device restarts or displays the Apple logo or a spinning gear unexpectedly
Note the Contact Support link in the article if it doesn’t help.
Why my phone turn off but the battrery still full