A:Answer You may not be able to, because the manufacturer's OS was not well-considered. The tablet ships with a voice-controlled keyboard, rather than an actual working on-screen keyboard. The voice-controlled keyboard fails, and in any event doesn't work for entering PINs. But resetting the device requires entry of a PIN.
You cannot fix this, because doing so would require using a different keyboard. But using a different keyboard requires you to login to the Google Play Store... which you cannot do because the keyboard doesn't work.
The failure of the manufacturer to include a working on screen keyboard with their tablet is a significant design defect. Your best opportunity for relief is to sue the manufacturer and Best Buy, or write your Senator and demand legislation protecting people from products that ship broken and without easily-serviceable parts and software.
