LG GC-399SLQW refrigerator - very unpleasant smell on the back of the refrigerat

Hello,

I have an LG GC-399SLQW refrigerator. It is a no frost fridge. For some time now, it has been emitting an unpleasant smell, even a stench. Not from inside the utility refrigerator, but from the back bottom. The refrigerator is under warranty, but the LG service "failed" me - it was found that I was using the refrigerator incorrectly.
The refrigerator was washed and used properly.
I have a question: what could be causing this smell?
There is no container on the back of the refrigerator for collecting water (I read on the internet that this water that does not evaporate completely can "stink").
It seems to me that it is possible to unscrew the sheet metal at the back at the bottom - is there a container under it that I could clean on my own?
Thanks for every tip.

Nothing ended your life there . The refrigerator has a lot of free space on the sides and rear.
I will just add that it seems to me that it feels more like the refrigerator turning on.
I would like to know if there is such a water tank in no frost refrigerators. If so, I am surprised that there is no better access to it.
As I wrote, the refrigerator is under warranty, I certainly wouldn't want to damage anything.

There is actually a plastic water tank at the bottom of the back of the refrigerator. Unfortunately, it cannot be removed at home. It was difficult to clean due to the obstructed access, but I managed to use a brush and a syringe to remove the water. The problem of unpleasant odors no longer occurs.
Thank you for your help.