Sony SGPT11 Series Help Manual page 48

Resetting Your Tablet Device
If your tablet device is not performing as expected, and you cannot force-quit your tablet device by pressing and
holding the power button for about 10 seconds, insert a pin or other slim object into the reset button (hole). You
will be able to force your tablet device to shut down.
Note
Pressing the reset button (hole) will not revert settings to factory default.
If you press the reset button (hole) and turn off your tablet device, unsaved data will be lost.