Hitler did not "instantly" become dictator. He was outranked by Hindenberg.
Hitler won the election in March 1933. The Night of the Long Knives occurred over a year later, and Hindenberg died a month after that, in August 1934.
Only then did Hitler have absolute power.
As it happened this day in history …
On 19 August 1934 about 95 percent of registered voters in Germany went to the polls and gave Hitler 38 million votes of approval (90 percent of the vote). Thus Hitler could claim he was Führer of the German nation by direct will of the people. He now wielded absolute power in Germany, beyond that of any prior traditional head of state. He had become, in effect, the law unto himself.