iPad won’t turn off after iPadOS 18.3 update

If your iPad is not operating as expected, begin with a forced-restart of your iPad - as this will often clear an isolated software issue:

Force restart iPad (models with Face ID or with Touch ID in the top button)

If your iPad doesn’t have the Home button, do the following:

1. Press and quickly release the volume button nearest to the top button.
2. Press and quickly release the volume button farthest from the top button.
3. Press and hold the top button.
4. When the Apple logo appears, release the top button.

If the problem persists after performing the restart, it may be necessary to reset your iPad settings. While this reset will not cause any loss of data, as a precaution, it is always wise to ensure that you have a current iCloud or iTunes backup before performing the reset:

How to back up your iPhone, iPad, and iPod touch - Apple Support

When you are happy to proceed, you can perform the reset from iPad settings:

Settings > General > Transfer or Reset iPad > Reset > Reset All Settings

If the problem still doesn’t clear, the next step is to reset the iPad to factory settings:

Restore your iPhone, iPad, or iPod to factory settings - Apple Support

Otherwise, you would be best advised to seek assistance directly from Apple Support. You can contact the Support Team using the Support link at top-right or bottom-left of this page. Alternatively and perhaps easier, you can initiate and manage your support cases using the excellent Apple Support App. If not already installed on your iPad, the App can be downloaded from the App Store:

https://apps.apple.com/app/apple-support/id1130498044

You might also visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to test and assess your iPad - and you can explore your available options:

Genius Bar Reservation and Apple Support Options - Apple

之前我也遇到類似跟你一樣相同的問題，但是後來我就是先做排查排除一切的可能我先將我們的手機打開然後把你所有下載的東西以及你不要用的App一一刪除對那千萬不要有因為任何的一些突然一個通知來，然後你就會心想他是叫我不要去刪除還是什麼的不是按照自己的想法去做，因為我以前有出現過類似這種情況就是突然一個訊息來是是不是某個官方叫我不要去刪除他的東西所以當手機出現很奇怪的時候我們打開手機將我們的手機應用程式一併刪除，如果還不能解決你的問題就是手機重置重置之後還是不能解決就直接跟官方人員聯繫看要怎麼處理這是最快的方式我是這樣處理啦，希望這個問題能幫你解決到。