Hello Serdar,
actually my solution was simple: there is one more circuit board inside macbook which is responsive for displaying battery charge with green led lights when you press the button. When it is damaged it may confuse the mainboard that charging is not working or no battery at all. The magsafe unit and the mainboard still may work properly, even if liquid damaged.
In my case I simply disconnected this led lights circuit from the mainboard and the macbook started charging the battery.
Later I carefully washed this circuit AND the mainboard + magsafe module with DISTILLED water, let it dry two days and things worked again, including the led lights.