I don't blame you for the turtle's small size and weak resistance. Generally, it is difficult to survive at home and the environment is strict. Both water temperature and water quality are required. I have raised more than n turtles so small, and the last turtle 10cm has been healthy for 9 years. I suggest you get a bigger one. After that, my family raised three turtles for 9 years, and the largest one was 27cm.
Let me show you my two families.