First off he identified American and Soviet societies, where he saw 'the same etcetera of indifference' - a statement of the urgency of German distinctiveness.
Then, under denazification, with his books and pension seized, he re-wrote the argument to say that he had misunderstood the trajectory of Hitler's regime, and really it was the inauthentic machine society that he thought he saw in the USSR and America. By that sleight of hand, his own anti-Modernist thought (in many ways just a cryptically worded reflex of romantic conservatism) was used to distance him from Fascism, as previously he had used it to embrace the NSDAP against Bolshevism and Capitalism. This, of course, was the alibi prepared for his denazification trial - prepared in correspondence with Hannah Arendt, if I remember right.
Later she re-worked Heidegger's old guff up into her theory of totalitarianism (along with some of the Brandler-ite Marxism she took of her partner of the time to make it sound a bit radical).