XPS 9570 back from repair, fingerprint scanner not working

First question:  does the sensor appear in the control panel?

If not, contact the repairer to have it checked internally.  It may have been left disconnected.

@ejn63​ Thanks for the question - I don't see it directly within control panel, but it appears under Biometric devices in the Device Manager. Within that it says "This device is working properly" and there is a record in Events of my re-installing the driver on 8/25.

Motherboard was replaced so same finger print data which was stored earlier will not work. This is working as designed by Microsoft. Before following below mentioned steps ensure you know the password of your Microsoft so that  you can avoid getting locked out. 

• First remove Pin from windows settings > Account > Sign in options 
• Once pin is removed please navigate to this directory 

•  C:\Windows\ServiceProfiles\LocalService\AppData\Local\Microsoft 
• You will find NGC folder please delete it. If it doesn't allow you to you  will have to change its permission. Once its deleted, please reboot the machine 
• Now setup pin and finger print sensor again 

@XPS_Man​ Thanks for the idea. I did what you recommended with the NGC folder, and there is still no response from the sensor. I get to the Windows Hello setup screen and there is no response from repeatedly lifting and resting my finger(s). 

@XPS_Man​ Sounds reasonable. It is within the 90-day warranty period of the repair. They offered to let me send it back to them for repair, but I would have to check if they would send someone instead. I am considering resetting the computer and re-installing Windows as a last check, as I have not done so since I bought it in 2018. Thoughts on that?

I don't think it would help. 

Here is what happened since my last note. I sent it back in to repair the fingerprint reader. They received it 9/6, performed tests and repair attempts, apparently ordered the wrong parts or parts that didn't fix the problem a number of times. On 10/3 they informed me they have not been able to fix the problem and will reset the computer to factory settings. I gave that OK, now they are saying they need to do the following repairs:

1. Palm rest hinge replacement, 2. Speakers and audio board replacement, 3. AC Adapter replacement

The support contact escalated the issue and they agreed to only charge for 3 ($35). I am currently asking whether these have anything to do with the fingerprint reader, whether they are needed, and if I will be able to use the computer normally if they perform these repairs. I told them that any extra issues that have arisen in the aftermath of the initial motherboard repair are Dell's responsibility and should be covered by them. Currently awaiting their response.

This what I get for trying to use a Dell longer than 4 years? 

Dell returned the computer to me on 10/13 with the following replacements: palm rest, motherboard, power switch board, audio board, speakers, AC adapter, fingerprint authentication cable. They also re-installed Windows 10 Home and tested for basic functionality. 

They set it up as a local account and did not provide instructions on getting up and running again. Should I:

1) go ahead and log in to Microsoft from the local account and set the PC up from there

2) create a new user and set up

3) reset Windows again and set up from the beginning

4) something else?

Thanks for your insight.