In Hell with 47

[Angrboda]

To be honest, I'm rather ignorant when it comes to political affairs.

So, my first question is: how do the checks and balances fit in order to prevent a leader dictatorship?

They don't. Generally speaking dictators tend to undermine Democratic norms through Democratic means. One example is through stacking the judiciary with loyalists and judges sympathetic to the dictator to be. We can see this in Trump appointing very conservative judges through a lackluster vetting process such as the vetting process in the Kavanaugh case. In Trump's current term he is set to appoint more such judges, likely including a Supreme Court justice. Trump has already asked for the ability to make recess appointments to departments and judgeships. While not illegal, this would further strip any checks that the Senate nominating process places on his appointments. At least one candidate for Senate majority leader has said he would agree to it.

A good example is current dictators like Victor Orban and arguably Benjamin Netanyahu. Both acquired power legally by undermining the constraints upon them legally.