Establish whether the fridge was powered, emptied, cleaned and left as its instructions require. The vacancy duration alone does not identify the source of the smell.
What the observation tells you
Forgotten food, damp fittings or an interrupted supply can create different conditions. Do not immediately add fragrance or run the appliance with suspect contents, because that can obscure the evidence. An electrical or chemical smell requires a different response from ordinary stale food odour.
A useful next step
Inspect only accessible storage areas safely and follow appropriate cleaning guidance. Describe the shutdown history and any visible damage when asking for help. Confirm suitable operation before restocking.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.