Hitlers interest in the occult began long before any of you think.
He was a boy during a time when Germans were falling in love again with thier own murdered pre christian past, the worship of old gods, the Sagas, pan
Germanic myths, legends, ect. This was joined by other persons interested in the occult, who added thier own brand of mystiscism. The runic alphabets,
ect, people were getting back in touch with thier pre christian roots.
Enter the organized hermetic occultists, who had already started the Golden dawn and Thule society. it was widespread in germany, there was nothing
unique about it, Wagners operas glorifying long dead heros and heroines of germanic lore. Hitler showed an interest in these things as a child, which
further developed, as he became an adult, into the lure of the more...twisted froms of it.
never heard he was hypnotized, tho I wouldnt doubt it, that a traumatic accident would make him have divine revalations and such, and given his
interest already in germanic legend, he would have taken it as a sure sign form the gods that he was meant for greater destiny.
Look in Germanic lore, myths, and legends for similar things....young heros being visited by Odin himself with Visions of what they msut do.
Possesion I doubt, since i do not believe in demons, thus, I do not believe it is possible to be taken over by something that does not exist.