Black screen after full UEFI flash

I saw this user had the same scenario but on other hardware

I have a similar issue

After connecting two solder points with some solder, which successfully disabled the HW write protect, and following the full UEFI flash process in the “chronos” shell, after a reboot my device just shows a black screen.

The screen is LCD-lit, but no content. The power button is lit and while charging via a 65W Thinkpad cable (instead of the original 45W cable) it got really hot after a workday sitting like this.

I already tried disconnecting the battery, emptying thr BIOS battery, resetting (power+refresh) multiple times.

I have

  • enabled developer mode
  • disabled HW WP
  • disabled Software WP
  • backed up the stock ROM
  • flashed the full UEFI ROM, probably not completely

I am wondering, if there might be something that is overseen.

My Chromebook is a 11th Gen Jasperlake Lenovo Flex 3, so not very new.

SuzyQ-cables seem to not be available anymore.

I have a CH341a programmer for my Thinkpad and could buy an additional WSON-8 probe to use that.

I have at least one Linux Laptop available to use Flashrom.

I am wondering what to do now. Restore stock ROM? Try hardware flashing the full Coreboot UEFI ROM, as software flashing may have some issue?

The device luckily wasnt very expensive. But I would absolutely want to fix this.

Any help appreciated.

could we add a “flashing” subcategory or tag? thanks!