In order to hard reset a Fujitsu Siemens T810, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Fujitsu Siemens T810 device will be brought back to the default configuration of a brand new device.
1. Start by taking off the phone's battery cover.
2. Now press the End button & Reset button (with a stylus) at the same time.
3. Release the End button when a new menu appears on screen.
4. Choose the Skip option, followed by Factory Defaults
5. Done! Your phone should now reset and restart.