I have a refridgerator that has a funky smell. Homeade fixes arent getting rid of odor. HELP?

The refridgerator is a 2.7 cubic foot (a mini fridge of decent size). My girlfriends parents had it and its near brand new. They stopped using it and left it unplugged with the door closed for a few months. Nothing was in it. They let us have it and we loaded it up. Upon drinking cans of soda and other things, we can smell the nasty odor from the refridgerator coming off of the cans and you can stand to drink the soda anymore. We have tried bleach and water, we tried leaving it outside in the sun + cold air for days to let it air out, and we also tried vinegar. Nothing has been successful so far. We cant figure it out and are ready to get rid of it, its just a very nice fridge and I dont want to have to buy a new one. Any other ideas on what could be causing the smell and how to get rid of it?

THANKS!