In order to hard reset a BenQ-Siemens EF71, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
BenQ-Siemens EF71 device will be brought back to the default configuration of a brand new device.
1. First, make sure that your phone is on.
2. Second, tap it this secret code - *#9999#
3. The phone will now restart.