This would require a very early Pod as German intelligence was notoriously bad, almost amateur.
The Soviets recognised the importance of spying and were excellent.The pod would be the Nazis binning Canaris and getting some one who could duplicate the Russian model of recruitment to get some very deep sympathizer moles in, early on.
Now let's say the Nazis know the time and the place of D-Day. This is a worse case scenario for the Allies but even with these advantages would the Germans have been able to stop the invasion?
If they amassed troops round the area, would that not be detected by ultra or air reconnaissance? Then the Allies would have to replan.
Or would the Germans follow written orders delivered by despatch riders and only move at night to heavily camouflaged positions?
This is a worse case scenario for the Allies but even with these advantages would the Germans have been able to stop the invasion?