water get inside the car...

Hi, everybody! I am new here. 5 days ago I owned Infiniti M30, 1991. Now I have the problem- I can't start the car. I think the problem is becouse of the raining. I leaved one window a little bit open and the water get inside. What do you think, shall I wait until it will get dry or my electric system is broken and I need to change it? Did anybody have the problem like this? Thank you.
I am sorry about my bad english.

3 months later...did that car dry out yet? I think I've had problems with rain coming in window and going into electrical controls on door panel (J30). Also water in tail lites a problem. Mine eventually dries out I think. Definitely do NOT need to replace whole electrical system!!