Some combination of an unmarked grave and cremation IIRC. The Soviets at one point believed they had parts of his body, but IIRC there was confusion on the ground and they wound up dumped somewhere and lost. AFAIK the supposed skull fragments in storage got ruled out by DNA testing.

It's reasonable to conclude that he really did die and get disposed of. For all the Nazis the western allies and their client states sheltered after the war it wasn't really all that secret so much as there was a whole lot of collective pretending that it didn't happen, and for all that a few high profile ones managed to disappear for a few decades there's no way Hitler could have kept things quiet: he was a brain poisoned dumb guy that stood out as unhinged in a pack full of brain poisoned dumb guys, he wouldn't have accepted comfortable obscurity and the inconvenience of proper opsec even if he was capable of it in the first place and so surely would have left traces or tried to rally other displaced Nazis to join up with the local Fascist party or the like.

The most likely story if he did try to flee was that someone along the way killed him (or he died on his own somehow) and left him in an unmarked grave to avoid the heat of dealing with him.