Dell 3120 Shim process

Question

We've received multiple system boards from Dell for 3120 chromebooks and are unable to use the provided shim tool. It errors out saying invalid action when trying to install it.  I've tried just resetting the serial number on the board and I get an error saying Flashrom is in an unknown state. I've removed the bracket and install the write protect screw and it does not work. I contacted support and the only answer was to send the device in.  I would really like to be able to replace system boards myself as it is a faster repair time. Any suggestions?

ksarnld · Accepted Answer

I was able to press 'm' to reset on the shim menu (once I found a working one) and after that the shim worked.

anne_droid · Answer

Hi

An internet search offers this...........

To use the Dell RMA shim on a Chromebook 11 3120, the usual flow is: disable write protect, insert the shim USB key, boot into recovery with Esc + Refresh + Power, then follow the on-screen prompts to write the service tag and reload ChromeOS.

What matters for the 3120

Dell’s documented shim process for similar Chromebook models says the shim is used after a system board replacement to restore the Service Tag, VPD, and ChromeOS, and the USB key normally comes with the replacement board or service part. For the 3120 specifically, community reports indicate the RMA shim file is often not publicly posted by Dell, so if you only have the bare file name or a generic USB image, it may not be enough without the correct Dell-issued shim package for that board.

Typical procedure

Remove write protect first, because the shim will not proceed properly if write protection is still enabled.
Plug in the RMA shim USB key.
Hold Esc + Refresh + Power for about 2 seconds to enter recovery/shim boot.
When prompted, continue into the shim installer and complete the service-tag/write process.

Common failure points

Wrong model-specific shim, because Dell shims are board/model specific.
Write protect still enabled.
Using aftermarket or mismatched parts that cause the shim hardware checks to fail, which technicians have reported on other Dell/ChromeOS RMA workflows.

Practical note

If you are trying to repair a Chromebook 11 3120 with no official Dell USB key, the most reliable path is usually the exact board-specific shim package that matches that model and board revision, not a generic ChromeOS recovery image.

ksarnld · Answer

@anne_droid​ Yeah, I've done all that. It seems to be an issue with the 3120's only, I've done 100s of 3100's without issue.  I'm not sure if it's an issue with the shims they are sending or if the write protect screw or flashrom are at fault.

anne_droid · Answer

https://www.dell.com/support/kbdoc/en-us/000209812/chromebook-3110-and-3110-2-in-1-rma-shim-process

Coupla extracts .....

Note: If you are running the RMA Shim after replacing the system board, you do not have to follow the steps below to disable Write Protect.

Replacement system boards are shipped with Write Protect disabled by default.

AND/OR

Note: Some replacement system boards are shipped in Developer Mode and with Write Protect (WP) disabled. Instead of displaying the Recovery Screen, the Chromebook boots from the RMA Shim USB key and load the CrOS Factory Shim setup menu. If you see the CrOS Factory Shim setup menu, then go to Installing the RMA Shim.

JohnnyBa · Answer

Shimming simplified version:

Step 1: disconnect usbc power supply, disconnect battery, and install Write Protection Screw.

Step 2: Reconnect Battery, Reconnect Power supply, and Press ESC+ Refresh + Power, you will see a prompt to recovery using internet or external DO NOT USE SHIM YET, instead just press Control + D to Enter Developer Mode.

Attention to this step: If you device does not enter DEV Mode, or due to policy that because you installed the wrong screw into the Write Protection, use a screw that will short-circuit all the 4 solder points in the WP screw hole.

Step 3: Dev Mode will get you into Chrome OS, do not Login to the system, instead insert the SHIM RMA the very specific one send by Dell for that device, and press ESC+Refresh+Power.

If the storage SDA is healthy it will automatically load the SHIM as Boot load and go to factory mode.

what is the SHIM VPD for: only for the new motherboard sent by Dell. what if you mixed them up old and new.

load Chrome OS (Don't Login) you should see device with SN# 1234567 as default VPD when you press Ctrl+V.

Notes: I have seen Dell 3120 after entering Dev Mode asking user to boot using internal storage or external. Dev mode has to run using the internal storage first then load the shim. So start up Chrome OS in Dev Mode first, then plugin shim and reboot.

Factory mode should go through the entire process, GRT verification which is last step might fail, remove the screw then re-finalize it takes several minutes but it should tell you to disconnect power cord when it's done.

Chromebook