Facial recognition and pin not working for login

I have NO idea where to put this one, and I can't find anything online.

Dell Precision 7740. 5 months old. Dell has replaced the motherboard twice, second time MB and memory. It's working today, but the facial recognition and pin don't work. They haven't worked since the first MB replacement.

The technician that replaced the MB told me it wouldn't work 'til it was re-set up.

Login using password. Go to Accounts>Sign in options. It SAYS my pin is there. I have removed it and recreated it.
Open Windows Hello face and hit set up. Opens and says "Get Started". Hit that. It pops up and requires my PIN. I enter it, it flashes and disappears...

At LOGIN, in the sign-in options is the Pin. When I select the Pin I get:
Your PIN is no longer available due to a change to the security settings on this device. You can set up your PIN again by going to Settings > Accounts > Sign-in Options...

I've BEEN in the *&^%$#@ sign-in options over and over. It SAID my pin was set. I changed it. I rebooted. I still can't log in with the pin. I tried again to set the facial recognition. It has me enter the pin then closes.

What does changing the motherboard have to do with using a pin or facial recognition in the first place? And WHAT do I have to do to get this thing to accept the pin and use the Windows hello face?

The motherboard will have the TPM or Trusted Platform Module. It is something which comes with your motherboard but theoretically works in insolation therefore compartmentalizing it's operation from everything else, at least in theory, making it harder to mess around with it. It's used basically for generating cryptographic keys for Windows which encrypts lots of things and therefore prevents bad guys from being able to see sensitive information. Windows Hello will use TPM to encrypt your login information, including biometrics and everything else.

Did the technician reinstall the necessary drivers for the motherboard? There will be many that will need checking and/or updating and/or installing. I'm thinking that might be the first port of call in fixing this issue as it sounds like a hardware issue, not a software one. Have you ran Windows Update and made sure to install optional software? This option will scan your computer for stuff that is not solely Microsoft related ie webcam, sound card, graphics driver, motherboard drivers etc. It should be the first thing that should be done upon booting into a new system and a system which has been in repair because often times a repair can simply mean a factory reset which in turn may also remove the most recent software Windows needs, and the hardware most importantly, needs to work properly.

Give it a try. Go to Windows Update and tick the optional software option. Check for updates and see what comes back. If your computer starts downloading lots of new things like drivers etc you know it's been reset and hasn't been updated since it was reset. I'm a little disappointed on your behalf that Dell, a HUGE billion dollar company, cannot ensure the laptop works properly and their customer can login with something as seemingly trivial (compared to more complex issues) like Windows Hello. You'd think it would be a piece of cake for a trained tech to fix this issue.

If he did mention the motherboard and it being replaced then it's likely the culprit. It does make sense as Windows will rely on hardware, specifically TPM, to properly run features like Windows Hello. Have you tried to see if BitLocker works? BitLocker also uses TPM as well and so you could perform a test to see if that particular part of the motherboard (TPM) is working properly or whether it's something else ie the configuration of Windows itself.

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Also...
Here's Dell official driver page for your laptop
Run through the list and find out your laptop might need.

https://www.dell.com/support/home/en...laptop/drivers

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Edit again..
You'll need to know the specs of your particular laptop in order to get the right drivers for the hardware installed. There will be variants of your laptop model each with their own different hardware components ie hard drive, graphics card etc.

The tech didn't change any drivers or anything else. It was strictly a "pull the laptop apart, yank the motherboard out, stick in the new one, put it back together. He's done it twice now, so he's gotten pretty fast. The second time Dell sent one 16GB stick of memory 'cause they were going to replace that with the motherboard... The system has 32, so the tech guessed and replaced the closest one....

But NO drives, no nothing else. I can't say the TPM HASN'T done something odd, but I try not to mess with it.

I'll go out to Dell and see if there are new drivers for the TPM and/or control vault or whatever. Can't hurt. (well, it can, but hopefully I won't mess it up)...