Samsung side by side fridge freezer rsa1dtmg stopped cooling

My Samsung side by side fridge freezer - RSA1DTMG  suddenly stopped cooling. The temperature  was flashing.  I initially attributed the decrease in cooling to the door being left slightly open (drawer being not closed properly). However, a few hours later, the temperature was still increasing in the freezer section and  then the fridge compartment temperatures started increasing.  After speaking to customer service at Samsung, I switched off the plug for an hour to reset. However this did not make any difference. The temperatures now on both sides are increased (21 degrees Celsius for freezer and 17 degrees Celsius for fridge). The lights in the unit is working. There are no unusual sounds coming from the fridge. The fridge is exactly 3.5 yrs old.