Thinkpads Forum

Hello All!

I am writing this because I flashed Coreboot to my T420 a number of months ago. In this process I used a CH314a programmer, some wires, and a contact patch on the underside of the laptop in the area around the palmrest. My coreboot worked very well, except that it had a glitch where the keyboard would stop responding for certain keys after a while using the laptop. After investing in a new keyboard and finding the problem continues, I have made the decision to re-flash the original bios (which I kept on my drive for just this occasion).

Here is where my problem comes in, I can no longer find the resource I originally used to flash my bios and I can't recall the proper setups for each pin and contact. I have had my laptop disassembled on my kitchen table for a week now.

If anyone on this site can help me find this resource, or even just tell me how to orient my programmer to the contact pegs on the laptop, I would be very grateful.

- Greencap

Make a bootable CD or USB-stick with this BIOS: https://download.lenovo.com/pccbbs/mobiles/83uj33us.iso

RealBlackStuff wrote: ↑

Fri May 19, 2023 2:02 am

Make a bootable CD or USB-stick with this BIOS: https://download.lenovo.com/pccbbs/mobiles/83uj33us.iso

I tried the CD method but it would just get to "Starting DR DOS", spit some text out, then blank to a black screen before I could read it and hang. When I can get to a computer that will take Rufus, I will try the USB method (because dd doesn't seem to want to write the disk image in a bootable state)

You can't just DD an ISO onto a CD, it needs to be 'burned' using a proper program.
In Windows, to burn a CD, use a program like ImgBurn.
Or make a bootable USB using Rufus.
In Linux, to burn a CD, use a program like ImgBurn under Wine.
Or make a bootable USB using Etcher.

The BIOS chip (W25Q64CVSSIG) has an indentation in one corner to mark pin 1.
The 8-pin cable should have a red wire to mark pin 1.
For more CH341A info, see this: https://winraid.level1techs.com/t/guide ... mmer/32948