HELP: My GE (gss20iembww) is not cooling and freezer is only cool

I have GE refrigerator (gss20iembww) with 2 door and ice maker. It did stop cooling and the refrigerator side stopped getting cold and the freezer side is only cool.

I did replace the defrost heater and cleaned the condenser coil and replaced the main control board but the problem still there. I can hear it going and i see the condenser fan going fine and everything seems to be working but i'm not sure why still not getting cold and why the freezer won't freeze.?? What else could it be wrong with it?

Any idea for help would be greatly appreciated before i have to get someone to fix it and pay a lot