Could I have the model number please. Are you saying that there were two wires that he removed from the heater and he wasnt sure which way around when he needed to connect the new heater element?
If you can give me the product code for you fridge I can let you have a wiring diagram which should help you work out which goes where.
Product code starts 92108
OK attached are two diagrams the first on is the original for your specific appliance but only available in German, the second one which is not for your model but is the same is in English. The only pair of brown wires I can see are those to the AC heater element which may explain why the unit is not working --