Hi there - that's an unfortunate issue to have. You mentioned that you shut down your phone, but have you tried a soft reset?
The soft reset is the same thing as pulling your battery (on devices where that is possible). This method will not remove anything at all from your phone and is completely safe to attempt in any problem situation.
You perform the soft reset by having your phone turned on. Then press and hold the volume down + power buttons until your phone vibrates and restarts. Note that you should not touch the device screen during the process (not even when the 'slide down to power off' prompt appears).
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