In order to hard reset a BenQ A500, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
BenQ A500 device will be brought back to the default configuration of a brand new device.
1. Turn off the phone.
2. Open Dialer.
3. Enter the *#9999# code and confirm with Call button.
4. The phone will now restart. Finito.