samsung srs2028 freezer playing up?

my samsung srs 2028 model stopped freezing and the fridge was also warm the temperature display was also flashing. i called an engineer who turned it off and back on the flashing then stopped and it started to get down to the required temperatures but only temporarily then it defrosted again can anyone help or have any information for me ive been told i may require a new board but i would like this confirmed before i pay out the money to have it replaced and it may not be the problem thanks