Chapter 2. Important Service Information; Overview Of The Chromebook Usb Repair Shim; Creating The Repair Shim; Removing And Reinstalling The Write-Protect Screw - Lenovo Chromebook 300e Chromebook Hardware Maintenance Manual

Chapter 2. Important service information

Overview of the Chromebook USB repair shim

You can use a Chromebook USB repair shim (hereafter referred to as the repair shim) as the recovery solution
on the Chrome OS operating system.
The repair shim is a bootable device that is required to service the computer. The repair shim is used for the
following purposes:
• Diagnose problems and restore the system to the factory-default settings.
• Refresh the system with the latest firmware and software.
The repair shim is not necessary when a Customer Replaceable Unit (CRU) is replaced. If a non-CRU is
broken, or there is a strong suspicion that a particular non-CRU is defective, it can be replaced directly.
Otherwise, the repair shim must be used to diagnose problems before any non-CRU is replaced.
The following is the list of CRUs for your computer:
1. ac power adapter
2. Power cord
3. Bottom cover
4. Upper Case (with keyboard)
For CRU definition, see "Chapter 5. Removing a FRU or CRU" on page 29.
For information about how to use the repair shim, see "Using the repair shim" on page 20.

Creating the repair shim

As a Lenovo service technician, do the following to create the repair shim:
1. Prepare a USB storage device formatted in FAT32 and with at least 8 gigabyte (GB) space. The required
USB storage capacity depends on the size of the recovery image.
Attention: Creating the repair shim will delete all data stored on the USB device. To avoid data loss,
make a backup copy of all the data that you want to keep.
2. Download latest version of the repair shim image from the Lenovo Support Web site at:
http://www.lenovo.com/support to create a repair shim. A Lenovo service credential is required.
Note: Ensure that you create the repair shim using the latest version of the repair shim image. Using an
earlier version might cause the repair process to fail.
3. Extract the downloaded file that contains the repair shim image.
4. Download the Win32 Disk Imager tool from http://sourceforge.net/projects/win32diskimager/.
5. Run the imager tool and follow the on-screen instructions to create the repair shim.
6. After using the repair shim, if you want to recover normal usage of the USB storage device, you will need
to format the device. Otherwise, you cannot use the storage space on the device.

Removing and reinstalling the write-protect screw

By default, the on-board Read-Only Memories (ROMs) are set as write-protected. Before refreshing the
Chromebook firmware, set the ROMs as unprotected by removing the write-protect screw on the system
board. After the refresh, reinstall the write-protect screw.
Attention: Turn off the computer before removing the write-protect screw.
To remove the write-protect screw, do the following:
1. Disable the built-in battery. See "Remove the battery pack" on page 31.
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