Chromebook screen is not working after flashrom -E

[Kyungtae Kim]

Hello,

My Pixelbookgo recently has this screen issue after accidently erashing flash memory using flashrom -E. Even though nothing shows up on the display screen,
(white) light is on when the power cable is plugged in and
serial consoles (e.g., /dev/ttyUSBX) are still accessible via suzyq cable.

I tried several things to resolve this, like pressing key combinations, re-flashing (and rebooting) ec from the workstation connected with DUT, etc, but unfortunatley nothing can recover the screen.

I hope this is not a physical HW issue. Any help at all would be greatly appreciated. Thank you.

(I just attached "version" information below just in case.)

> version  (from ttyUSB0)

Chip:    g cr50 B2-C

Board:   0

RO_A:    0.0.10/29d77172

RO_B:  * 0.0.11/4d655eab

RW_A:    Error

RW_B:  * 0.5.30/cr50_v1.9311_mp.7-535187521e

BID A:   00000000:00000000:00000000 Yes

BID B:   00000000:00000000:00000000 Yes

Build:   0.5.30/cr50_v1.9311_mp.7-535187521e

         tpm2:v1.9308_26_0.55-aced358

         cryptoc:v1.9308_26_0.7-8af3e03

         2021-05-28 01:22:54 @chromeos-ci-factory-us-central2-

> version   (from ttyUSB2)

Chip:    Nuvoton NPCX796F B.02

Board:   7

RO:      atlas_v2.0.8910-557b9dd40

RW:      atlas_v2.0.8910-557b9dd40

Build:   atlas_v2.0.8910-557b9dd40

         2021-05-22 01:29:45 kkim@kkim-Modern-14-A10M

Regards,
Kyungtae

[Peter Marheine]

Which flash did you accidentally erase? Since your EC is alive and you don't mention trying to flash AP firmware, it looks like you erased the AP flash so the main processor can't boot. Flashing your AP firmware (emerge chromeos-bootimage) will probably help, though completely erasing the AP flash will also have erased data that normally doesn't get touched which you'll probably need to manually rebuild. In particular, the VPD section contains the system serial number that you'll probably need to reprogram.

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[Kyungtae Kim]

Thanks for the answer, Peter.  

I don't think I speicified some targets other than -E option when doing "flashrom". That seemed to end up erasing AP firmware unfortunately. 

The following link can help find out private data like VPD, I guess. 

https://chromium.googlesource.com/chromiumos/platform/ec/+/cr50_stab/docs/case_closed_debugging_cr50.md#flashap 

and Im not sure about this, but please let me know if some prebuilt AP firmware images are available for PixelbookGo online.

Regards,
Kyungtae

[Peter Marheine]

I'm not sure if they're available anywhere else, but you can definitely get the AP firmware image out of an OS image- the chromeos-firmwareupdate tool is a self-extracting zip containing firmware images that you should be able to extract with your favorite unzipping tool and should be able to manually extract from an OS image.

[Kyungtae Kim]

It worked. Thank you. 

Regards,

Kyungtae