X1 Carbon 4th Gen -- Wonky Keyboard

[Scorpion8]

Doing some work on resurrecting yet another X1 Carbon. This one is a 4th Gen i5 - 8GB model. The previous owner broke out completely the Wifi card socket (sheesh, some people). I had a new spare mobo, so installed that, ran all the updates (repeatedly) and it's working fine (almost). Here's the issue and another question.

The issue is the keyboard works fine, except for the numbers row. And sometimes the Fn keys. For example, making changes in BIOS I cannot use F10 to save and reboot, but once the computer is up and running, the Fn keys work fine for their assigned task (volume, wifi on/off, etc). And then none of the number keys work. Odd sort of divisions in what works and what doesn't. I've tried reseating the cables. No joy. There doesn't appear to be sugar/syrup/drink debris, so..... thoughts? New cable? Doesn't appear to be pinched or broken anywhere.

And the general question: The UG and HMM both talk about replacing the mobo you need to re-establish the machine number, and it gives you a website for the software tool and then says "Only a Lenovo Technician can access this". The machine runs fine, the new mobo has it's own unique serial number. Is it truly important to re-establish what it was before the hardware swap? Neither (old or new) will be in-warranty so am not concerned about that.

[RealBlackStuff]

Download the HMD: https://download.lenovo.com/ibmdl/pub/p ... tm38us.exe and install it temporarily on the laptop.
Plug in an empty small USB-stick (32-64MB is enough).
In the downloaded files is a program usbfmtpw.exe, run that to make a "Maintenance key".
Cold-boot the X1 from that to enter the old Model and S/N.

[Scorpion8]

Thanks for that info, which I d/l'ed. But is it necessary for any reason? What does re-establishing the old serial number do for me that just using the new serial number doesn't?

[RealBlackStuff]

If you want to run Lenovo updates, they won't work without that info.
It is the Lenovo MTM and S/N which is important, not the mobo S/N.

[Scorpion8]

Odd, because Vantage updates have worked fine. I even registered the unit on Lenovo's website and it recognizes the new serial # and system type (20FB) just fine.

Any thoughts on the keyboard issue? Odd that it affects just a single row of keys, and the entire row, not individual keys.

[RealBlackStuff]

You wrote: "I had a new spare mobo", but maybe that was a used mobo?
Because brand new ones do NOT have their MTM and S/N on it.
Go here and enter the new S/N without a dash.
What info do you get?
As for the keyboard, either a spill on the KB, dirt in the KB-cable socket or a KB gone bad.