In order to hard reset a Bird S198, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Bird S198 device will be brought back to the default configuration of a brand new device.
1. Turn your phone on.
2. Use the phone's keyboard to enter one of those codes: *#77218114# or *#881188# or *#94267357# or *#9426*357# or *#19912006# or *#118811# or *#3646633#
3. Give your phone a moment to restart. Finito.