Lenovo 21JN Manuals

Manuals and User Guides for Lenovo 21JN. We have 1 Lenovo 21JN manual available for free PDF download: Hardware Maintenance Manual

Lenovo 21JN Hardware Maintenance Manual

Lenovo 21JN Hardware Maintenance Manual (108 pages)

Brand: Lenovo | Category: Laptop | Size: 58.92 MB

Table of Contents

Table of Contents
3
About this Manual
5
Chapter 1. Safety Information

7
Chapter 2. Important Service Information

25
Chapter 3. General Checkout

27
- What to Do First
  27
- Checkout Guide
  28
- Diagnosing Problems
  28
- Quick Test Programs
  29
- UEFI Diagnostic Program
  29
- Bootable Diagnostic Programs
  30
- Power System Checkout
  30
- Checking the Ac Power Adapter
  31
- Checking the Built-In Battery and Operational Charging
  31
- Checking the Coin-Cell Battery
  31
Chapter 4. Related Service Information

33
- Reset or Restore Windows
  33
- Passwords
  33
- Power-On Password
  33
- Nvme Passwords
  33
- Supervisor Password
  34
- System Management Password
  34
- How to Remove the Power-On Password
  35
- How to Remove the Nvme Password
  35
- How to Remove the System Management Password
  35
- Power Management
  36
- Sleep Mode
  36
- Hibernation Mode
  36
- Symptom-To-FRU Index
  37
- Numeric Error Codes
  38
- Error Messages
  39
- Beep Errors
  39
- Beep Symptoms
  41
- LCD-Related Symptoms
  42
- Intermittent Problems
  43
- Undetermined Problems
  43
Chapter 5. Special Keys

45
Chapter 6. Locations

47
- Locating Computer Controls and Connectors
  47
- Front View
  47
- Side View
  49
- Locating Frus and Crus
  52
- Major Frus and Crus
  53
- LCD Frus and Crus
  57
- Miscellaneous Parts
  59
- Connector and Cable Guide
  59
- Looking up FRU Information
  62
Chapter 7. FRU Replacement Notices

63
- Service Tool Kit
  63
- Screw Notices
  63
- Retaining Serial Numbers
  64
- Restoring the Serial Number of the System Unit
  64
- Retaining the UUID
  65
- Reading or Writing the ECA Information
  65
Chapter 8. Removing or Replacing a FRU

67
Appendix A. Notices

103
Appendix B. Abbreviation Table

105

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