The most common cause of this fault on these is the fridge evaporator ices up to much and this causes the fridge to go warmer just like its doing now.
What you need to do if fixing it yourself is empty the fridge section fully.
From there you need to remove the plastic cover in the fridge at the back in the bottom have.
You will need to remove the water bottle (if fitted) and there will be 2 screws at the bottom of the panel.
Then remove the vent cover on the panel and theres another screw in there either side.
Then you can remove the cover ad disconnect the fan wiring. Now if its iced up it can be stiff to remove due to the ice.
Once you have removed the panel you will see the evaporator. If this is all iced up use a hairdyer and melt it all.
Then make sure theres no ice in the panel as well blocking the fan up.
Then refit the panel and retry the appliance and that should get it going again from there.
But if you dont want to go removing panels then you need to fully defrost it. Turn the appliance off for 24 hours and leave the fridge door open and this will defrost itself from there.
Then after 24 hours turn it on and then you will be able to set the corect temperture in there and it should start to work again.
Try that and see how it goes and let me know.