You definitely went too cold. At 20°C and 50% humidity the dew point is about 9°C (see
this calculator for example). If you cool below the dew point you get condensation. Basically you ended up with water inside your camera.
1. Let the camera dry thoroughly. Put it in a non-dusty place with the lens off (and no lens-cap) so it can dry faster. Without battery. Use desiccant (or rice) next to it to absorb moisture faster.
2. Never cool below the dew point or you will get condensation.
3. All commercial cameras are sealed and filled with argon or some other gas. When we were playing with the cold-finger cooled 450Ds the best idea for the deep cooling was to seal the camera in a plastic bag with desiccant and to fill the bag with argon gas (you can get the gas from Bunnings, the regulator came from eBay). Seal the bag as well as you can. I remember having -5°C at the back of the sensor without issues. The main thing was keeping the camera dry. There were always leaks but usually I could get 2 nights before needing to refill the argon.
Hope this helps.