Chapter 5. Removing A Fru Or Cru; General Guidelines; Hardware Identity; Prerequisite For Replacing A Fru - Lenovo Chromebook 300e Chromebook Hardware Maintenance Manual

Chapter 5. Removing a FRU or CRU

General guidelines

When removing or replacing a FRU, ensure that you observe the following general guidelines:
1. Do not try to service any computer unless you have been trained and certified. An untrained person runs
the risk of damaging parts.
2. Begin by removing any FRUs that have to be removed before replacing the failing FRU. Any such FRUs
are listed at the beginning of each FRU replacement procedure. Remove them in the order in which they
are listed.
3. Follow the correct sequence in the steps for removing a FRU, as shown in the illustrations by the numbers
in square callouts.
4. When removing a FRU, move it in the direction as shown by the arrow in the illustration.
5. To install a new FRU in place, perform the removal procedure in reverse and follow any notes that pertain
to replacement.
6. When replacing a FRU, carefully retain and reuse all screws. If screws are missing, look up the Lenovo
parts numbers in "Appendix C. Lenovo part numbers for CRUs and miscellaneous parts" on page 45 for
replacement screws and order them through the Lenovo CRM system.
7. When replacing the base cover, reapply all labels that come with the replacement base cover. If some
original labels are not included with the replacement base cover, peal them off from the original base cover
and paste them on the replacement base cover. Refer to "Appendix D. Label locations" on page 47 for
the layout of labels on the back side of the base cover.

Hardware identity

A set of valid hardware identities (HWIDs) are provided by Google. Google logs the exact hardware
combination into a Chromebook and creates a HWID. The HWID is used to ensure that all parts are valid
during the repair of the Chromebook. The HWID is used for the following purposes:
• Auto-update new patches and software for the lifetime of the computer
• Recover the computer to the factory default settings
If unauthorized parts are installed, you might not get the correct auto-updates for your computer, or you
might not recover your computer successfully to the factory default settings. For example, if you install a
different model of the wireless LAN card, which is not the required configuration, the HWID will not match.
HWID is checked by using the repair shim. For information about the repair shim, see "Overview of the
Chromebook USB repair shim" on page 19.

Prerequisite for replacing a FRU

Use the repair shim before replacing any non-CRUs. The following is the list of CRUs for your Chromebook:
1. ac power adapter
2. Power cord
3. Bottom cover
For information about how to use the repair shim, see "Using the repair shim" on page 20.
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