Exactly what they should have done. Return an error in the driver framework's evtDeviceStart (or similar...), let DeviceManager show the "device could not start

Exactly what they should have done. Return an error in the driver framework's evtDeviceStart (or similar...), let DeviceManager show the "device could not start" icon and write a "You are using a non-genuine USB to UART chip..." to the eventlog.