How can I fix my Defy TWIIN freezer fault light flashing ?

What could be the problem, with my DEFY TWINN freezer.
the contoller board was replaced by appliance technician, but the freezer still give problems.
1. After a hour or so the fault light start flashing and keep on flashing, the freezers however starts freezing but the freezer will start to freez up which it is not supose to do as this model does not show any freezing(ice) inside the unit.
2.The top part will then start to defrost, if the bottom freezer unit is cover plate is removed, it is completly iced up.
3. Could it be that the new control board was wronly coneccted or that the sensors are not at he correct possition.
4. Who can help with a Wiring diagram for this Defy Twiin Freeze.
NB. If the ice is cleaned out it opperates for +-2weeks before starting with same symtoms as explained above
Is there help out there
Henning