The iPhone repeatedly has white apples (boot loops or "white apple loops") and does not enter the system, usually due to system update failures, software glitches, or hardware issues. Here are some steps to fix it:
Force restarting can fix many temporary software issues and won't delete data on your phone:
iPhone 8 and later models: Quickly press and release the volume plus button, then quickly press and release the volume down button, then press and hold the side button until you see the Apple logo.
iPhone 7 and iPhone 7 Plus: Press and hold the volume down button and the side power button at the same time until you see the Apple logo.
iPhone 6S and previous models: Press and hold the Home button and the top (or side) power button at the same time until you see the Apple logo.
Updating iOS via iTunes or Finder may fix the white apple loop caused by software issues:
Connect your iPhone to the computer with a data cable.
Open iTunes (on Windows or earlier versions of macOS) or Finder (on macOS Catalina and later).
Select your device. iTunes or Finder may prompt you to update or restore your iPhone.
Select "Update" to try reinstalling iOS without deleting your data.
If the update is not successful, you can try to put your iPhone into recovery mode and restore it via iTunes or Finder:
Connect your iPhone to your computer and enter the force restart operation mentioned above, but after seeing the Apple logo, keep holding the button until you enter the recovery mode screen.
iTunes or Finder will prompt "problematic iPhone" needs to be updated or restored.
Select "Recover". Note that this will erase the data and settings on your device.
If recovery mode still doesn't solve the problem, you can try using DFU mode for a more thorough recovery. DFU mode will completely overload your iPhone software and firmware, but will also completely erase all data:
Connect your iPhone to the computer and let it enter DFU mode. Different models of iPhone have different ways to enter DFU mode, and the specific operation can be searched.
Once you successfully enter DFU mode, iTunes or Finder will prompt you to restore your iPhone.
If none of the above methods solve the problem, it may be caused by a hardware failure. In this case, it is recommended to contact official Apple support or go to a nearby Apple retail store or authorized service provider for assistance.
Please note that these steps may result in data loss if your data is not backed up before the recovery operation. If you don't feel confident that you're doing these things on your own, it's always wise to seek professional help.