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Hold the three buttons at the same time; then after 7-10 seconds, you will see the picture below. When you see the picture, please release three buttons.
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2. Then will go into Recovery Mode. See the picture below.
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D2s:
Make sure your device is off. You can open the cover from the back side, then you will see the reset button
hold power button and reset button the same time until you see the picture below. Then release themthe buttons.
After couple seconds, system will go to Reboot menu Recovery Menu (see the below picture); then select factory reset
after that, click OK to restart device.
V2s_Plus:
NO Recovery Menu