In order to hard reset a BenQ-Siemens M81, 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 M81 device will be brought back to the default configuration of a brand new device.
1. Switch your phone on.
2. Type in the *#9999# code.
3. The phone will now reboot. Grats, the hard reset is complete.