Is it common that iPhone won't turn off even with hard reset? Yes, if this problem occurs it means that there is a problem with the software or hardware of the phone. If your phone is still working, you can try to restore it to factory settings.
Your battery is low. Your iPhone is running out of storage space. Certain apps are incompatible with your software. Your operating system is outdated.
Press and quickly release the volume up button. Press and quickly release the volume down button. Press and hold the side button until you see the Apple logo.
On most phones, press your phone's power button for about 30 seconds, or until your phone restarts.
It terminates all running apps without allowing them to “clean up” any process in progress, so it can cause data loss in apps that are running (just like it can on a computer). But it won't cause any damage to hardware or iOS. The better way to restart (unless the phone is frozen) is to shut down, then start.
With Jamf Now, you can remotely restart or shut down enrolled devices. These remote commands require a supervised iPad with iPadOS 10.3 or later, a supervised iPhone with iOS 10.3 or later, or a Mac with macOS 10.13 or later.
If your iPhone 8 keeps freezing when you open a specific app, there may be a problem with that app and not your iPhone. Try uninstalling and reinstalling the app or look for an app update. If neither of these work, you may need to find an alternative app.
Many of the current iPhone 8 problems are extremely common. We're seeing complaints about sound issues, wonky battery life, problems with Bluetooth, 3D Touch issues, random reboots, and more.
If your iPhone, iPad, iPod touch, Mac, or Apple Watch is lost or stolen, you can erase it in Find Devices on iCloud.com.