Need Custom BIOS (UEFI/Dualboot) for Lenovo Chromebook 100e Gen 3

[GuiTi]

Hey everyone!
I need help with my Lenovo Chromebook 100e Gen 3.
Here are the details:

• Motherboard: LA-L131P
• MFG Date: 2022/01/07
• MTM: 82J80001BR
• MO: MPNXB2103001
• Factory ID: LI123

I bought a new Winbond 25Q128FVSG chip.
The chip currently on the board is the same model but with different ending letters.
I can’t use the CH341 clip on the chip that’s on the board because it’s too low-profile and doesn’t make proper contact.

The Chromebook is Google account locked, and I’ve already tried everything.
I understand that I need to replace or flash the BIOS.

I’m looking for a custom BIOS that supports UEFI and dual-boot.
I’d like to flash the full UEFI BIOS from MrChromebox, but I can’t run his utility since I can’t access ChromeOS.

Do you have this BIOS and could share it with me?
Or any other UEFI-compatible / dual-boot BIOS that works with this board?
Any suggestions are welcome!

Thanks in advance!

[SMDFlea]

If you post the bios backup we might be able to unlock it, then you can do what you want after that. You will need to desolder the bios and put it in or on an adpater board or use a WSON pogo adapter with an SPI programmer.

[GuiTi]

Hi SMDFlea,
Thanks for your reply. Pulling the BIOS from the chip will be difficult because the chip is very low-profile and there aren’t accessible pads to attach the CH341 clip.

On this board there’s a white coating over the area where the WP jumper should be — do you know if the write-protect (WP) is located there? Could I jumper that spot to disable WP, or can you explain how to disable it using the battery instead?

I tried disabling the battery and entering Advanced Mode, but the Chromebook just flashes the red charging LEDs. My procedure was: disconnect the battery, power the Chromebook on, and as soon as the screen lit I disconnected the battery. In Advanced Mode I tried to switch to Dev Mode and it reported that it was already in Dev Mode, but I couldn’t get to the boot options.

If you can suggest a way to do this without removing the chip, that would be hugely appreciated. Thanks!