My name is***** will assist you.
I am sorry to hear that happened.
This sounds like the firmware has glitched, you will need to do a restore. Please follow these steps>With the device turned off, press and hold the Volume Up
While holding the Volume Up key, press and hold the Power key.
Release both keys when the Recovery Booting message is displayed in the top left corner and the Galaxy Tab 3 logo appears.
Press the Volume Down key to scroll to wipe data/factory reset.
With wipe data/factory reset highlighted, press the Power key
Press the Volume Down
key to scroll to Yes --delete all user data
, and then press the Power
Once the wipe is complete, press the Power
key to select reboot system now
The master reset is now complete. The device will restart.
Then you can sign back in with google to restore your data.
Please let me know if you need any other assistance.
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Thank you very much!