Like most things in Brazilian history, it was nothing radical but a gradual process. There was aways resistance, be by rhetoric with artists, professors, intellectuals that were forced to leave the country (Brazil has a great tradition of protest music, like Chico Buarque, Caetano Veloso, etc), and even armed resistance, like the current president Dilma Rousseff. Since the late 70's, the military government started a democratization process and the last military president João Figueiredo established an amnesty law that gradually brought back anti-government Brazilians, and announced that the next president would be a civil one, but chosen by congress, not direct election. The opposition in congress began to become more vocal and around 1983, with politicians, artists and intellectuals leading it, the Diretas Já movement started, that resulted in massive protests demanding direct elections, those protests weren't repressed like they used to be, indicating a change in how the government dealt with the rebellious population. The movement wasn't successful, but the elected president, Tancredo Neves was in the opposition party, but with a conciliatory discourse. He died of cancer right before the inauguration day, and the vice took the job, but that's a different story. The first direct election was in 1989, but it is said that the dictatorship ended in 1985 when Tancredo was elected as the first civil president since the 60's. Just a curious fact, the two main candidates in the Last elections were Dilma, that was in armed guerrilla and Aécio Neves, the grandson of Tancredo.