Lenovo X240s, User Manual

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3. Inspect the ac power adapter. Check for any physical damage, and ensure that the power cable is firmly
attached to the adapter brick and the computer.
4. Verify the ac power source is working by attaching another device to the outlet.
If your computer does not run on battery power, check the following items:
1. If the battery runs out of power, attach ac power adapter to recharge the battery.
2. If the battery is charged but the computer does not run, call Lenovo Customer Service Center to have
it serviced.
A power button problem
Problem : The system does not respond, and you cannot turn off the computer.
Solution : Turn off the computer by pressing and holding the power button for four seconds or more. If the
system is still not reset, remove the ac power adapter and reset the system by inserting one end of a
needle or a straightened paper clip into the emergency reset hole. To locate the emergency reset hole, refer
to “Bottom view” on page 6.
Boot problems
Print these instructions now and keep them with your computer for reference later.
If you receive an error message before the operating system loads, follow the appropriate corrective actions
for power-on self-test (POST) error messages. See “Error messages” on page 106.
If you receive an error message while the operating system is loading the desktop configuration after the
POST is completed, check the following items:
1. Go to the Lenovo Support Web site at http://www.lenovo.com/support and search for the error message.
2. Go to the Microsoft Knowledge Base homepage at http://support.microsoft.com/ and search for the
error message.
Sleep and hibernation problems
• Problem : The computer enters sleep mode unexpectedly.
Solution : If the microprocessor overheats, the computer automatically enters sleep mode to allow the
computer to cool and to protect the microprocessor and other internal components. Check the settings
for sleep mode.
• Problem : The computer enters sleep mode immediately after the power-on self-test.
Solution : Ensure that:
– The battery is charged.
– The operating temperature is within the acceptable range. Refer to “Operating environment” on page
12.
If the battery is charged and the temperature is within range, have the computer serviced.
• Problem : A critical low-battery error occurs, and the computer immediately turns off.
Solution : The battery power is getting low. Connect the ac power adapter to the computer and plug it
into an electrical outlet.
• Problem : The computer display remains blank after you press Fn to return from sleep mode.
Solution : Check whether an external monitor was disconnected or turned off while the computer was
in sleep mode. If you disconnected or turned off the external monitor, connect it or turn it on before
resuming the computer from the sleep mode. When resuming the computer from the sleep mode
Chapter 9
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Troubleshooting computer problems
117