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Lets try to hard reset your ipad first. To do so, Hold down the sleep wake button, and home button for about 15 seconds until the device shows an apple sign, you can then release the buttons and it should shut down.
Start it again and then check if it still goes back to the cover picture.
If so, we may need to change this setting as well. Go to Settings, General, Auto lock. And set the duration to five or ten minutes. A long enough time that the screen lockout shouldnt affect your usage.
Once that change is set, let me know if your ipad still exhibits the same symptoms.
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Senior Technician and Network Switching Systems Operator / Maintainer.