The CB 500 has a two variations of the motherboard associated with this device. Version 1 (Picture 1.1) does not have the jumper connector, it does on the other hand have the developer switch on the right side of the device. When the developer switch is in the on position the tech will be able to verify the SN of the device but if the device has the Version 1 motherboard there is an additional command when disabling the read/write protection. It will be highlighted in green under "Once in command prompt"

The CB 500 with the Version 2 motherboard (Picture 1.2) does have the jumper on the motherboard which is the read/write protector. This connector must be jumped and the developer mode switch on the right side in the on position, the switch is towards the back of the device, if it’s towards the front it's in the off position. (Picture 1.3) before you put the CB 500 into developer mode and change the SN. If you do not, the SN will not save, show and error message, and also corrupt the OS. If this happens reinstall the OS and make sure the jumper is jumped and the developer switch is in the correct position

Picture 1.3

Get to developer mode: Chromebook XE500C21

Make sure you have placed the developer switch in the correct position before moving on to the next steps! Picture 1.2 on the previous page shows the location of the jumper connector.

Developer switch: Picture 1.3

The developer switch enables the command line shell. The switch is behind a little door on the right-hand side of the chromebook. To enable the developer switch you open the door, use something pointy to move the switch towards the back of the device, and reboot. Note: be gentle! Some people have reported that the developer switch breaks easily.

The first time you reboot after turning the developer switch on, your chromebook will show an ominous warning that its software cannot be trusted, this is because the command line shell is enabled. From here, complete the following steps:

• • Press Ctrl + D

  • This process will erase all personal data on the "stateful partition" (i.e., user accounts and settings - no worries, though, since all other data is stored in the cloud!).

  • Wait 5 - 10 minutes while the device prepares itself for developer mode.

The erase and wait steps only happen when you first enable the developer switch, to help prevent someone from quickly reimaging your device while you're away from the keyboard. Successive boots will:

• • Show the same scary warning

    • Press Ctrl + D

  • Continue to boot only Google-signed images, and only from the SSD.

To get to the command prompt:

• • Wait until the device boots to the Chrome start screen.

    • Press Ctrl + Alt + → (Ctrl-Alt-F2)

Once in the command prompt continue to the next page, if not in a command prompt retry the above steps.

Once in the Command Prompt: Chromebook XE500C21

Type as shown below, if it’s Capital leave it Capital, if its lowercase leave it lowercase. Spaces are important make sure if there is a space you type it in the terminal.

To get root acess:

Type: chronos

• • Press Enter

Type: sudo su

• • Space after “sudo”.

  • Press Enter

For the Version 1 motherboard Start Here! (This may or may not work, seems to vary for each board. We will keep this updated with any changes)

1: Type: flashrom --wp-status

Press Enter

This will show you if the read/write protection is enabled or disabled.

2: Type: flashrom --wp-disable

Press Enter

3: Type: flashrom --wp-range 0 0

Press Enter

Now the read/write is disabled. to enable type: flashrom --wp-enable

4: Continue to Type: vpd -l below.

For the Version 2 motherboard Start Here!

• Type: vpd -l (lowercase L)

• Space after “vpd”.

• Once you type vpd -l, this will display the current motherboards information including the motherboards current serial number.

• Press Enter

• Type: vpd -s “serial_number”=”0000000000”

• Replace the 000’s with the Device Serial number from the original device

• Space after “vpd”, Space after “-s”.

• Make sure the serial number is CAPITAL letters.

• Press Enter

• Type: vpd -d “Product_S/N”

• Space after “vpd”, Space after “-d”.

• Press Enter

• If flashromPartialWrite() error displays go back to where the jumper is placed and make sure it is securely in. Re-seat it to make sure.

• Type: dump_vpd_log --force

• Space after “dump_vpd_log”.

• Press Enter

• Type: dump_vpd_log --full --stdout

• Space after “dump_vpd_log”, Space after “--full”.

• Press Enter

We have come across an issue where the Samsung 500 won't stay in dev mode when the jumper is taken out. This is a problem because when you send it to Q/C, we cannot verify the serial number. From now on, please bring the device to one of the Q/C techs or myself to verify before you pull the jumper out. Be sure to notate on the work order which one of us you brought it to.

To close the command line session, type EXIT to close shell and EXIT to close the terminal.

Put the developer switch back into the off position (button towards the front of the laptop)

Remove the jumper.

Re-screw the bottom plate back onto the device.