HP Elite Dragonfly 13.5 Maintenance and Service Guide - Page 68

Understand the issue, Boot up sequence, Failure classification, Table 6-4, Failure, classification

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1. Understand the issue It is important to understand the issue that occurred, including related symptoms. It helps to understand the basic computer boot-up sequence as well as the failure itself. Boot up sequence The computer performs several steps after you press the power button or restart the computer. It is important to understand where in the boot-up sequence the symptoms occur. The following table lists the phases of the boot-up sequence and explains the symptoms that may occur in each phase. For example, a blue screen error (BSOD) often occurs during the performance phase. Table 6-3 Boot-up sequence and associated failures Item Procedure Startup After you press the power button, the computer boots after all internal power rails (such as 5 V, 3.3 V) are stable. Confirm that power lights are on and fan is spinning. POST (UEFI/BIOS) Common issues: all lights are off; troubleshooting lights are on; computer does not boot; video is absent. Power-On Self-Test (POST) verifies that hardware components (such as processor, hard drive, memory) are functional. When POST is complete, the HP logo appears briefly and then disappears. If there are errors, the computer may exhibit blinking lights and POST error messages, and so on. Common issues: lights blink; error message appears; system hangs (lock up or freezes) Performance (operating system) System boots to operating system, and Windows logo screen appears. Common issues: hangs, blue screen, distorted video, driver conflict, slow performance, display issue (dead pixel), I/O issue (no speaker sound), wireless/audio unavailable, noise. See Analyze the issue on page 62 table for detailed troubleshooting information. Failure classification Failure classification is a breakdown of different types of failures and symptoms that could occur during the boot-up sequence. Table 6-4 Failure classification by boot-up sequence on page 60 and Table 6-5 Failure classification by hardware devices on page 60 represent the failure classification for common notebook failures. Table 6-4 Failure classification by boot-up sequence on page 60 categorizes failures by the boot-up sequence. 1. Power-on: Common issues are no power, recycle, or reboot. 2. POST: Common issues are no boot (despite power), light flash, or diagnostics error. 3. Performance: Common issues are Intermittent Loss of Power, Blue Screen, Hang. In many cases, issues can be identified and associated with particular hardware (for example, display or storage). Table 6-5 Failure classification by hardware devices on page 60 categorizes failures by hardware: ● Display ● I/O (input/output) devices 1. Understand the issue 59

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1. Understand the issue
It is important to understand the issue that occurred, including related symptoms. It helps to understand the
basic computer boot-up sequence as well as the failure itself.
Boot up sequence
The computer performs several steps after you press the power button or restart the computer.
It is important to understand where in the boot-up sequence the symptoms occur. The following table lists
the phases of the boot-up sequence and explains the symptoms that may occur in each phase. For example, a
blue screen error (BSOD) often occurs during the performance phase.
Table 6-3
Boot-up sequence and associated failures
Item
Procedure
Startup
After you press the power button, the computer boots after all internal power rails (such as 5 V, 3.3 V) are
stable.
Confirm that power lights are on and fan is spinning.
Common issues: all lights are off; troubleshooting lights are on; computer does not boot; video is absent.
POST (UEFI/BIOS)
Power-On Self-Test (POST) verifies that hardware components (such as processor, hard drive, memory) are
functional. When POST is complete, the HP logo appears briefly and then disappears.
If there are errors, the computer may exhibit blinking lights and POST error messages, and so on.
Common issues: lights blink; error message appears; system hangs (lock up or freezes)
Performance
(operating system)
System boots to operating system, and Windows logo screen appears.
Common issues: hangs, blue screen, distorted video, driver conflict, slow performance, display issue (dead
pixel), I/O issue (no speaker sound), wireless/audio unavailable, noise.
See
Analyze the issue
on page
62
table for detailed troubleshooting information.
Failure classification
Failure classification
is a breakdown of different types of failures and symptoms that could occur during the
boot-up sequence.
Table 6-4
Failure
classification
by boot-up sequence
on page
60
and
Table 6-5
Failure
classification
by
hardware devices
on page
60
represent the failure classification for common notebook failures.
Table 6-4
Failure
classification
by boot-up sequence
on page
60
categorizes failures by the boot-up
sequence.
1.
Power-on: Common issues are no power, recycle, or reboot.
2.
POST: Common issues are no boot (despite power), light flash, or diagnostics error.
3.
Performance: Common issues are Intermittent Loss of Power, Blue Screen, Hang. In many cases, issues
can be identified and associated with particular hardware (for example, display or storage).
Table 6-5
Failure
classification
by hardware devices
on page
60
categorizes failures by hardware:
●
Display
●
I/O (input/output) devices
1. Understand the issue
59