Buzzing noise

That buzzing noise you hear means the fan inside the refrigerator compartment isn’t running properly which is why the noise goes away when the door is opened since the fan stops when the door isn’t closed. You will need to remove the entire back vent panel INSIDE the refrigerator. If there is ice/frost build up behind this panel, use a hair dryer and thaw it all out. If you find no build up, replace the fan motor which is part 404C on the diagram I attached below.