The only way at this moment to unlock the phone is through factory reset. It has been confirmed that resetting the lock through Google is ineffective because you will need Internet access (unavailable in most of the cases). You can hard reset the phone by turning it off then press all the buttons: Volume Down + Menu button + Power button. When you see the Recovery menu, use volume buttons to select and Power to confirm. Choose Wipe Data/Factory Reset. Confirm the procedure and the phone will reboot.