Try a Reset to factory settingon the tablet. Either using a paper clip or push Pin or by pressing a combination of buttons. Try to look first for a very small circular hole on the side or rear of the tablet and poke then hold for about a minute while the tablet is still turn on and the tablet will restart itself.
The second option is to press combination of buttons to access the on screen menu of the tablet.
First, turn off the tablet. 1. Press and hold the power button and quickly poke the reset hole until you see an Android logo on screen.
Use the paper clip to poke the hole to navigate until you go in to the Wipe data or Factory reset, The 6th option from above. Use the power button to select 3. Select the Delete all user data and restart and it will process it then select restart/reboot after the reset.