What software is needed to open the tablet when holding down the power key simultaneously with the volume button does not work?
Are you sure it's charged/charging? That's the first thing to check. Are there any other symptoms or error messages?
how it is dead, is it charging? if there is no battery left you cant do much
How To Fix Your Soft-Bricked Android Device – First Aid Guide
Hold down power button for more than 15 seconds.
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