Check to see if there is a Reset button on your tablet. Usually it will be next to Power or Volume buttons. Use a small Pin to insert, press, and HOLD it for 15 seconds. Your tablet should reboot. See if it will reset your tablet and let you log into your tablet.
If that does not work, press and hold Power button until your tablet turns off completely. Press and hold Volume Down + Power at the same time for 15-20 seconds. See if the Recovery menu will comes up.
If still not working, power off again. Press and hold Volume Up + Power buttons for 15-20 seconds.
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Check to see if there is a Reset button on your tablet. Usually it will be next to Power or Volume buttons. Use a small Pin to insert, press, and HOLD it for 15 seconds. Your tablet should reboot. See if it will reset your tablet and let you log into your tablet.
If that does not work, press and hold Power button until your tablet turns off completely. Press and hold Volume Down + Power at the same time for 15-20 seconds. See if the Recovery menu will comes up.
If still not working, power off again. Press and hold Volume Up + Power buttons for 15-20 seconds.