Samsung refrigerator freezer not freezing

I have never owned a fridge freezer so have no experience to draw on apart from a sketchy knowledge of the principles involved.

I just wanted to mention that food remaining frozen at -2 C or even -6 C doesn't mean the food will remain safe to eat indefinitely, in fact the safe life of food at those temperatures will be about the same as in the freezer compartment of the old fashioned fridge - a matter of a few weeks to a couple of months.

The safe and almost indefinite storage of freezer food requires temperature of -25/-27 C

I suggest you obtain service for your fridge freezer...

This is a twin cool unit. refrigerator works independently from freezer unless compressor failure so compressor is not the problem. you may have a defrost problem or an evaporator fan failure in the freezer easy way to check open door hold the door switch and listen for fan draft if you hear it is good is not you have a bad fan or a bad door switch. the refrigerator has a defrost problem usually is the sensor you try that the other thing can be the heating element but rarely goes bad.
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According to the picture posted the freezer defrost is stuck on. Why it would not get cold enough. Contact a local appliance repairman and get professional help as this should require control board repair/replace.

The fridge gets its cold air from the freezer through a vent(damper) between the freezer and fridge.The fan in the freezer blows air through it. Make sure this fan is running. You may have to hold the door switch in for it to run. There is a flap you adjust with the fridge temp. control. Make sure it's opening and closing when you adjust the fridge temp.
The problem could be the electronic control if you have one or the mechanical linkages.

Sounds like a main control board problem keeping the freezer fan from working . If no air flow to the top of the freezer , the icemaker will stop working and the ice will begin to melt ( leaking from freezer ) . The coils will start to freeze up due to no air flow across them . If continued for a period of time , the cold air could return thru the return vent located in the bottom of the ref/freezer section and freeze the water tank in the refrig section , causing the no water thru dispensor .

Replace your thermostat and will work like new again

Ice on the back wall indicates a problem with the defrost cycle. The ice builds up and starts to choke off the air flow, so your symptoms would indicate that may be happening.

Defrost problems are usually any of the three components, the heater element, the defrost termination temp switch, or the defrost timer.

Check defrost timer

-2 although below freezing temperature, is not really enough to keep food really frozen. I am presuming we are talking in Celcuis. You need to set the freezer to a lower setpoint.

Move the refrigerator to a room that is at least 50 degrees F.

Temps on most refrigerators are regulated by the fresh foods temp. If your garage is let's say 35 degrees, the fresh foods temp will most likely never raise enough to turn the refrigerator on. With the refrigerator never running, the freezer compartment will warm to 35 degrees, resulting in everything melting. Even if garage is a bit warmer, say 45, the refrig will not run long enough for the freezer to maintain a low enough temperture. If the garage temp falls to below freezing, say 20 degrees, the food in the fresh foods compartment will freeze. (outdoor beverage dispensers have internal heaters to prevent product from freezing !) Please don't rate this if not a Fix-Ya for you, as anything else lowers my score.