How did the Qin Dynasty end?

Actually, the most important reson is that there was a tyrant or fatuous ruler in its late years. The Emperor Ershi of the Qin Dynasty seemed to not bve able to rule the whoe country anymore. As a result, the peasant rebellion broke out to overthrow the reign.
Besides, the unfair social positions and the economic and political policies went agaist the wish of the people. So it can be considered as a must to end its rule for the Qin Dynasty then.