Strategy For Replacing A Hard Disk Drive; Important Notice For Replacing A System Board; How To Use Error Message - Lenovo ThinkPad T420 2620 Hardware Maintenance Manual

Attention: The setup configuration on the computer you are servicing may have been customized. Running
Automatic Configuration may alter the settings. Note the current configuration settings (using the View
Configuration option); then, when service has been completed, verify that those settings remain in effect.

Strategy for replacing a hard disk drive

Always try to run a low-level format before replacing a hard disk drive. This will cause all customer data on
the hard disk to be lost. Be sure that the customer has a current backup of the data before doing this task.
Attention: The drive startup sequence in the computer you are servicing may have been changed. Be
extremely careful during write operations such as copying, saving, or formatting. If you select an incorrect
drive, data or programs can be overwritten.

Important notice for replacing a system board

Some components mounted on a system board are very sensitive. Improper handling of a system board can
cause damage to those components, and may cause a system malfunction.
Attention: When handling a system board:
• Do not drop a system board or apply any excessive force to it.
• Avoid rough handling of any kind.
• Avoid bending a system board and hard pushing to prevent cracking at each BGA (Ball Grid Array) chipset.

How to use error message

Use the error codes displayed on the screen to diagnose failures. If more than one error code is displayed,
begin the diagnosis with the first error code. Whatever causes the first error code may also cause false error
codes. If no error code is displayed, see whether the error symptom is listed in the Symptom-to-FRU
Index for the computer you are servicing.
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ThinkPad T420 and T420i Hardware Maintenance Manual