replacing thermostat makes no difference?

I replaced my thermostat in my freezer as I had the red fault light permanently on. The food in the drawers were swimming in water. It does not seem to have made any difference. On number 3 the fridge temp goes up to 28 and if I change it to 2 it drops down to -5 but the motor stops running and the red light is still permanently on. What can I do next to rectify this so that I have a freezer that switches on and off and the red light goes off. Cannot aford to replace it for a new one. Any help would be grealty appreciated. Thanks you.