Lenovo IdeaPad Z400 Notebook - Manual (Page 31)

Chapter 4. Troubleshooting
27
The computer enters sleep
mode immediately after
Power-on self-test (POST). • Make sure that:
- The battery is charged.
- The operating temperature is within the acceptable range. See
“Chapter 2. Use and care Information” of Lenovo Safety and General
Information Guide.
Note: If the battery is charged and the temperature is within range, have the computer serviced.
The computer does not
return from sleep mode and
the computer does not work. • If your computer is in sleep mode, connect the AC adapter
to the computer, then press any key or the power button.
• If the system still does not return from sleep mode, your
system has stopped responding, and you cannot turn off the
computer; reset the computer. Unsaved data may be lost. To
reset the computer, press and hold the power button for 4
seconds or more. If the computer is still not reset, remove
the AC adapter.
Computer screen problems
The screen is blank. • Do the following:
- If you are using the AC adapter, or using the battery, and the
battery status indicator is on, press F12 to make the screen brighter.
- If the power indicator is in blinking, press the power button to
resume from the sleep mode.
- If the problem persists, follow the solution in the following
problem “The screen is unreadable or distorted.”
- Press F9 to confirm whether the backlight for the LCD screen has
been turned off.
The screen is unreadable or
distorted. • Make sure that:
- The display device driver is installed correctly.
- The screen resolution and color quality are correctly set.
- The monitor type is correct.
Incorrect characters appear
on the screen. • Did you install the operating system or programs correctly?
If they are installed and configured correctly, have the
computer serviced.
Sound problems
No sound can be heard from
the speaker even when the
volume is turned up. • Make sure that:
- The Mute function is off.
- The headphone jack is not used.
- Speakers are selected as the playback device.
Battery problems
Your computer shuts down
before the battery status
indicator shows empty.
-or-
Your computer operates after
the battery status indicator
shows empty. • Discharge and recharge the battery.