I think you have to start your Microsoft Surface in safe mode.
How to enter safe mode
1. To activate safe mode, press and hold the power key until the power off icon appears.
2. Tap and hold the power off icon until the Safe Mode prompt appears.
3. Select Safe Mode to confirm.
Try to log in with your PIN.
Try the tips Microsoft wrote there : https://support.microsoft.com/en-us/surface/troubleshoot-problems-with-windows-hello-on-surface-3346b3eb-6dd5-3d5e-e219-d47e790ef09b