Ice often builds up behind the back panel, there is often a small element which is designed stop the build up of ice (hence being frost free) but they dont often work from my experience. The water from the melted ice should not be a problem, as the electrics are located on the outside (under the fridge). There is often a condensation drain which takes the water away into a dish at the back of the unit where the compressor is, it is worth checking that this dish which sits on top of the compressor isnt full of water.
However I can confirm any water\moisture or ice inside the fridge compartment should not pose an electrical risk, as they are built with this in mind.
Please let me know if I can be of any further assistance