1.Switch off the device by holding the Power button.
2.Next, press & hold Volum Down + Volume Up + Power buttons together for a couple seconds.
3. Release Power key when you see an Acer logo on your screen.
4. Keep holding the Volume Up and Volume Down keys until the Android System Recovery screen appears.
5. Yay, you now should see Recovery Mode menu.
6. Use Volume buttons to scroll Power button to select options.