You can put a fan and a lamp in there to warm it up and speed the melting of any frost. Just make sure the light bulb does not get too close to any plastic.

If there are air passages, try to look inside to see if something is in there. In higher end fridges uUsually there is a knob that controls how much cold from the freezer goes into the refrigerator. It should be set in mid range or #5 to start.