> Hitler came to power via a democratic process. He won an election fair and square.
Debatable. In Weimar Germany’s last free and fair election, the NSDAP won the most seats, but failed to win a majority. von Papen, who was leader of the Centre Party (a centre-right Catholic party), convinced President von Hindenburg to appoint Hitler Chancellor. Neither von Papen nor von Hindenburg were Nazis; they thought they could control Hitler, they found out too late that rather than controlling Hitler, Hitler was controlling them. President von Hindenburg died in office of old age, at which point Hitler decided Germany didn’t need a President any more to keep the Chancellor in check. After the Nazis banned his own Centre Party, von Papen accepted the inevitable, joined the Nazi Party and spent the war as German ambassador to Turkey. At no point did the majority of Germans vote for Hitler in a free and fair election.
> What America has is not democracy, it's a system of checks and balances.
Weimar Germany had checks and balances too, it is just they didn't work. There is no guarantee that America's will forever continue to work either.
And America is a democracy. Some people want to define "democracy" in a very narrow sense to exclude any checks and balances, but that's not usual contemporary English usage. It is the same as these people who pedantically insist that "America is a republic not a democracy", ignoring that in saying that they are using the word "democracy" in a narrower sense than normal. In the normal sense of "democracy", it includes systems which aren't pure democracies, that moderate democracy with checks and balances such as judicial review, representative rather direct democracy, etc – which are very common worldwide, far from being unique to the US