Hitler was Austrian. How did he become the head of state of Germany?

Hitler immigrated to Germany and became a German citizen. At that time, Germany did not stipulate that foreigners who immigrated could not run for the head of state. Foreigners who immigrate now are not even qualified to run for public office. Unless you were born in that country and obtained nationality. Obama was born in Kenya and his ancestors immigrated to the United States, so Obama was born in the United States and can run for president. Because the American Constitution stipulates that immigrants are not eligible to run for the presidency of the United States, only those who were born in the United States and have American citizenship are eligible.