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a. Disconnect the ac power adapter and all cables from the computer.
b. Close the computer display, and turn the computer over.
c. Remove the memory module. Refer to “Replacing a memory module” on page 64.
d. Remove the M.2 cards. Refer to “Replacing an M.2 wireless LAN card” on page 65 and “Replacing
an M.2 wireless WAN card” on page 68.
e. Remove the hard disk drive. Refer to “Replacing the hard disk drive or solid-state drive” on page 62.
f. Wait for 30 seconds, and then reinstall the memory module and the known good battery or the ac
power adapter to test the computer with minimal devices attached rst.
g. Reinstall each device one at a time that you have removed in the earlier steps.
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 4 seconds or more. If the
system is still not reset, remove the ac power adapter and the battery.
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 POST error messages.
If you receive an error message while the operating system is loading the desktop conguration 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
11
.
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
Chapter 10. Troubleshooting computer problems 129