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 first.

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 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 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

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Lenovo 20AA000BUS, T431s, 20AA000MUS manual Power button problem, Boot problems, Sleep and hibernation problems
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20AA, T431s, 20AA000MUS, 20AA000BUS specifications

The Lenovo ThinkPad series has long been a favorite among business professionals and tech enthusiasts alike, and the Lenovo 20AA000BUS, 20AA000MUS, and T431s models exemplify the brand's commitment to innovation, performance, and rugged design. These laptops are designed for enterprise users who require reliability and versatility in their everyday tasks.

The Lenovo 20AA000BUS model features a robust Intel Core processor that ensures smooth multitasking and quick application launches. Paired with a generous amount of RAM, users can easily run demanding applications and simultaneously manage numerous browser tabs without a hitch. The full HD display provides sharp visuals and vibrant colors which enhance productivity, whether one is working on spreadsheets, watching videos, or conducting presentations.

In terms of connectivity, these models boast several USB ports, HDMI output, and an SD card reader, which facilitate seamless integration with various peripherals and external devices. With the inclusion of robust wireless options, including Wi-Fi and Bluetooth, users can stay connected throughout their workspaces and collaborate effortlessly with coworkers.

Security features are a priority for Lenovo, and the 20AA000MUS model does not disappoint. Built with a fingerprint reader and a webcam privacy shutter, users can feel confident in their data safety. Lenovo's Trusted Platform Module (TPM) technology further enhances system security by encrypting sensitive data.

The T431s, a prominent model in this lineup, prides itself on its sleek and lightweight design, making it easily portable for professionals on the go. The carbon fiber and magnesium alloy chassis not only lends to its durability but also ensures that it withstands the rigors of daily travel.

Battery life is another highlight of these models, capable of lasting through an entire workday, which is a significant advantage for users who often find themselves away from power sources. The Quick Charge feature allows for rapid recharging, ensuring that users can quickly power up their devices before heading into meetings or events.

Overall, the Lenovo 20AA000BUS, 20AA000MUS, and T431s represent a blend of advanced technology, user-centric design, and robust security features. They stand out as reliable companions for professionals seeking efficiency and performance in their computing devices. Whether in the office or on the move, these laptops meet the demanding needs of the modern workforce.
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