As described, your iPad or its battery may have fault requiring further investigation - but before exploring this possibility, there are some steps that are some worth trying...
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:
- Press and quickly release the volume button nearest to the top button.
- Press and quickly release the volume button farthest from the top button.
- Press and hold the top button.
- When the Apple logo appears, release the top button.
Force restart iPad (models with the Home button)
Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
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 restore the iPad to factory settings. This is a full reset - and will completely reinstall the most recent version of iPadOS supported by your iPad:
Restore your iPhone, iPad, or iPod to factory settings - Apple Support
At the end of the factory restore process, you have opportunity to restore from your backup. As a diagnostic exercise, you would be best advised to initially not restore the backup, but instead to setup as a new iPad with your AppleID. The objective is to start with a "clean" setup - and then established whether or not the battery drain issue persists.
a) If the problem persists after performing the factory restore with a clean setup, you would be best advised to seek assistance directly from Apple Support - and request a remote diagnostic test. 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
Alternatively, you might 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 explore your available options.
Genius Bar Reservation and Apple Support Options - Apple
b) If the problem has been resolved after performing the factory restore with a clean setup, now is the time to restore your backup to your ipad; the backup includes data and device settings:
Restore your iPhone, iPad, or iPod touch from a backup - Apple Support
If the problem does not return after restoring your backup, you might reasonably assume that a corruption of the installed OS was the cause of the issue. By contrast, if the problem returns, there is an issue with your device settings.
