Nokia 6.1 stock flashfile (Oreo 8.1)

Get the Google USB driver and platform tools 

Extract the platform tools zip file to C:\adb

Open PowerShell

 .\adb devices

If the device is connected properly proceed to the next step, if not install the USB driver again

Note: you may need to install the driver while the device is in fastboot 

Files 

Extract the rom zip archive

put device in download mode connect to PC and hold volume down

.\fastboot devices 

Open online service tool (Nost) then just browse to the MLF file then tap next