1, volume up + 3 line button + power on
2, showing android logo,
3, press 3 line button
4, u got the android system recovery utility
5, go the (4th) option to wipe data/factory reset by pressing volume down button
6, select wipe data/factory reset by pressing 3line button
7, then select option yes by pressing volume down button
8, press the 3 line button to select the option YES,
9, after reset press reboot system now bye pressing 3 line key,
10, process DONE.....