In order to hard reset a BenQ-Siemens EF81, 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 EF81 device will be brought back to the default configuration of a brand new device.
1. Turn your phone on.
2. Now tap in this code: *#9999# or *#0009#
3. Enter your phone's lock code (default code is 0000).
4. Wait until your phone restarts. Done.