Press Power button once again.

Unlocking your screen

After turning on the LCD, the screen remains locked. You can unlock the
screen in the following way:
Press & hold the lock icon ( ) and slide it across the unlock icon (
).
You can also slide across other icons to allow quick and easy access
from the lock screen.
If you have set up a screen lock through one of the following ways as
Pattern, PIN, Face Unlock or Password, the method of unlocking the
screen will be different. See Security section for other ways to protect your
tablet and privacy.
Care and use of the battery
This section provides the important safety precautions in order to handle
your battery properly.
Refer to the enclosed Instruction Manual for Safety and Comfort for
detailed precautions and handling instructions.
The lithium ion battery can explode if not handled or disposed of
properly. Dispose of the battery as required by local ordinances or
regulations.
Charge the battery only in an ambient temperature between 5 and 35
degrees Celsius. Otherwise, the electrolyte solution might leak, battery
performance might deteriorate and the battery life might be shortened.
Never try to remove or replace the battery by yourself which may
possibly result in serious injury. Please contact an authorized Toshiba
service provider, if necessary.
Charging the battery
When the battery power becomes low, you must charge it to avoid losing
any data.

Procedure

You can charge the battery when the tablet is either on or off by connecting
the AC adaptor.
TOSHIBA AT300SE series
User's Manual 3-10