What has happened is the drain tube for the defrosted moisture, that is collected during the defrost cycle of your unit, has become plugged. When this happens the water builds up in the catch funnel till it over flows and then spills into the freezer compartment.
Toi fix this you need to locate the drain tube in the back of the unit.
Pull the unit away from the wall and unplug it (the power cord). Pull it out further till you have clear acces to the back of the unit. Useing a good bright flashlight. Look at the lower back and locate the compressor. Ir is a oval shaped thing that looks like a mini turkey roasting oven. Well sort of anyways. These are always painted black and some have the specification tags on them. Look ablve this and see if there is a pan or tray or anything that would hold water. Above that is the drain tube coming from the inside. you need to poke a wire up into that tube and unplug it. Be ready with some towels as there may be quite a bit of water that comes out when you unplug it.
Thats about it.
If this answer satisfies your question please click the accept button. I will not be paid if you dont.
You can always ask follow up questions after you accept. I will be here to answer them.
If for some reason you are not happy. Please tell me what I can do to put a smile on your face.
Thank you for using Just Answer. Please tell someone about us.
Best regards; The Home Smithy
After you have accepted it is important that you leave positive feedback.