Hitler became Chancellor due to his charismatic personality, his organizational genius, and his gift as a public speaker. These attributes enabled him to lead the National Socialist German Worker's Party (N.S.D.A.P., pejoratively known as "Nazi's") to win a substantial minority in the German Reichstag, so much so that no party won a majority. Under governmental system of Germany at the time, the leader of party with a controlling interest in the Reichstag became Chancellor. Because of an apparent political stalemate and because of Hitler's rising popularity (he had ran for President against Paul von Hindenburg and came in second, with 35% of the vote) von Hindenburg named him as Chancellor.
Hitler joined (but did not found) the N.S.D.A.P. while still on active duty at the end of World War I. He soon rose to prominence in the party because of his gifted oratory. In many speeches, Hitler railed against the unfairness of the Treaty of Versailles and the perceived incompetence of the Weimar Republic's government. At one point, Hitler led an armed movement to take over the government of Munich, the famous "beer hall putsch." The putsch failed almost immediately, and Hitler was sent to prison. While imprisoned, he dictated Mein Kampf to his cell mate. It became a best seller almost immediately, as it railed against the Versailles Treaty, as well as the Jewish bankers and communist aggressors who had crippled Germany. There is no relationship between Hitler's rise to power and the Wall Street crash, other than both were incidents of the Great Depression, which crippled Germany even worse than it did the United States. The sheer economic desperation of the Depression provided fertile ground for Hitler's rants. He did manage to make the N.S.D.A.P. a potent political force as a result of the economic chaos of the time. Only after his second place finish in the presidential race did influential German politicians urge von Hindenburg to name Hitler as Chancellor, something whch von Hindenburg did reluctantly.
The Weimar Republic Constitution provided for the Chancellor to assume dictatorial powers for a limited time in the event of a national emergency. The "national emergency" that developed was the fire which destroyed the Reichstag building, and was (correctly) blamed on Communist sympathizers. On the basis of this event, the Reichstag voted to award Hitler dictatorial powers which he never surrendered.
I can precise that after several dissolutions of the Reichstag, due to the incapacity of the democratic parties to unify their action against Hitler and his NSDAP, Hitler was named Chancelor by the President Hindenburg on the 30th of january 1933, after his party had got more or less 38% of the votes.
He immediately dissolved once more the Reichstag and got only 43% of the votes.
He purposed to suppress the communist party, and that was voted even by the socialists. The communists being excluded, the NSDAP had the majority and there was not any election later.