Record the known duration, the extent of opening and the condition of the contents. Newly formed frost is only one consequence; food storage and recovery need separate attention.
What the observation tells you
A narrow gap overnight differs from a brief fully open door during loading. Do not assume that closing it and silencing the alarm restores every item's safety. Nor should a later normal display erase the earlier event from the repair account.
A useful next step
Use official food-safety guidance, protect the contents and follow the model's recovery instructions. Seek assessment if cooling or ice accumulation does not return to normal behaviour.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.