Is there any accountability for ruler in Islam and if so, what is the model?

Reading the history, I have noticed that Islamic ruler are mostly tyrants rather than rulers. They have full control of all affairs. No one can defy them. There is no election. A descendent of the King is chosen by the King and it usually become Kingdom. Or someone has to defeat the ruling King to change the lineage. In modern world there are three branches of government. The head of state, the assembly and the judicial branch. There are checks and balances. Everyone does their own job. The head of state presides all affairs but he can be removed by Assembly. The Assembly makes the Law. The judicial branch make sure that Law is executed and that head of state be made accountable. My concern is Islam does not have a model where the masses can gain prosperity and happiness because of totalitarian model. The head of the state essentially becomes a terror. No one can say anything against him, even in a joke because he is everything. **In Islam how can a ruler be subjected to accountability?** For example in cases * He is suspected in killing someone * The ruler is suspected in squandering money * The ruler selected incapable people * It is suspected that the ruler has committed adultery. Are there any checks and balances on the ruler? If yes what are they. I have also heard (don't have the quote now) that in Islam, obeying the ruler is mandatory. That further suppresses masses if they want to raise their voices. **Are there any guidelines in Islam that would facilitate such accountability for ruler?**