Unbricking a Chromebook

[grimmute]

I am very new to ChromeOS and its alternatives so apologies if my question is very obvious. I just wanted to check in with the experts before I give up on this.

I have an Asus Chromebook Flip C434 and it doesn’t boot. It says “ChromeOS is missing or damaged”. I tried the Recovery Utility but it also failed after checking the USB with “an unexpected error”.

As far as I can tell, dev mode isn’t enabled on this Chromebook, since I can’t seem to open up any kind of terminal with CTRL + F2/F3 or with CTRL+T on the “OS verification is off” screen. It also doesn’t allow me to boot from USB.

Since I don’t know what I’m doing, I also tried removing the battery connection on the motherboard and try booting via the adapter directly. That way it entered an endless boot loop of the “OS verification is off” screen. Not sure what this indicates.

When I press CTRL + F2 during an error screen, I get some log screen and it says “SSD for installation not specified”.

Here are some more details in case it says something to you:

My questions:

1. Is there something I missed that I can try?
2. How can I verify if the eMMC is dead?

I have also seen a topic here and the OP seemed to have managed to revive the Chromebook and use an SD card to boot something else. This is what I would like to do as a last resort but I don’t have any of the mentioned tools for the process, nor I am technical enough to probably do this successfully.

Any help would be appreciated.

[MrChromebox]

the image posted shows the device in recovery mode because you booted it there via the recovery keys – that tells us nothing. power off, then power on normally, and let it fail and go to recovery, then press tab and take a picture of the upper left – that will tell you the reason it failed to boot.

[grimmute]

Hi @MrChromebox,

Here is the normal boot log:

Thank you very much for your help.

[MrChromebox]

ok, that means that the internal storage was found (not dead), but no valid copy of ChromeOS is found (likely due to the failed recovery)

the recovery USB has a small ~10mb linux partition that contains the recovery log(s), we’ll need to check that and see why it failed.

since this is a CR50/battery device, I would suggest trying to boot to recovery mode and performing a recovery with the internal battery disconnected.

[grimmute]

I get a boot loop when the battery isn’t connected. The “OS verification is off” screen keeps coming up and then the device shuts down.

I realized I could still enter Recovery while it’s doing this though!

On the recovery, it verified the USB device’s integrity and afterwards unfortunately failed again with “an unexpected error”.

Here is what I see when I press CTRL+F2 on that screen:

[MrChromebox]

this screen doesn’t tell me anything, need the recovery log to know what the error was

[grimmute]

Hi again @MrChromebox,

The problem is I’m not sure how to get that log. Would you let me know?

This is the other “log” screen on CTRL + F3 on the recovery error screen.

[grimmute]

I have just realized pressing CTRL + Shift + Up/Down scrolls up/down on this screen!

This seems to be where it errors:

[MrChromebox]

that screen is just the output of the script run with -x, it’s not as helpful as the actual log.

as I said, the recovery logs are saved on the recovery USB in the ~10mb partition.

[grimmute]

I see, sorry I didn’t catch it the first time you mentioned. It didn’t cross my mind the logs would be saved to the USB.

Here are the logs (not sure which one is relevant):

• dmesg: dmesg - Pastebin.com
• firmware: firmware - Pastebin.com
• progress: progress - Pastebin.com
• recovery: faaae27d - recovery

Thank you once again for helping.

[MrChromebox]

looks like the eMMC might be toast, it’s not finding any drives to install to

[grimmute]

That’s what I was also suspecting…

Is there a way to boot from USB/SD (without dev mode being enabled) or toggling the dev mode in this state?

Or is this now an expensive paper holder?

[MrChromebox]

You can flash the UEFI firmware via CCD/SuzyQ (same as if the device were bricked), and then boot from USB.

[grimmute]

I couldn’t find the SuzyQ where I am unfortunately.

I opened up the CB and found a “Winbond 25q128jvsq” on it. I believe this is the chip I need to flash something via ch341a? I went ahead and ordered a kit.

I have no clue how to do this yet but once it arrives, I’ll be going over the documentation and watch some beginner videos. Wish me luck!

As a side note, I also contacted ASUS in the meantime and they asked about €200 to repair this, basically 1/3 of what I paid when it was new…

[MrChromebox]

you can flash with a ch341a as well, just more difficult on some devices vs others depending on whether or not a chip clip can be used.

[Tayne]

You will need a pogo pin connector to flash the c434, wson 6x5

https://www.aliexpress.us/item/3256801644532228.html?gatewayAdapt=glo2usa4itemAdapt

[grimmute]

I ordered this set: https://www.aliexpress.com/item/1005007671365111.html

Doesn’t this have everything I need? Apologies if very obvious, I have never worked with these things before.

[Tayne]

No because your board uses a wson chip, which can’t be clipped onto with a chip clip. unless you plan to desolder the chip

[grimmute]

Would you let me know how I can verify that it’s a WSON chip?

Here is the pic of the chip, if I understood correctly this is the one I need to flash:

I thought the chip clip would just hold onto this and I would be able to flash. Wouldn’t that work because the chip isn’t “high” enough while it’s on the board? Or is it because it’s a different size?

The link you shared doesn’t seem to ship where I am. Would you let me know the exact part name I need? Apologies for many questions, these things look extremely complicated for my level.

[Tayne]

As you can see in the picture, the soic-8 chip has legs and that is the type of chip you can just clip on to.

Your CB uses the wson 6x5 chip which does not have legs so there’s nothing to clip on to.

The clip you need is a pogo pin adapter. Refer to the link I shared above for what it should look like or other names it may go by. You need one for a wson 6x5.