I'm not locating your model #, but on similar models it means the main control has not seen proper temps on the defrost cycle in the Freezer (FZ) section.

Take a look at the rear wall of the FZ, is it covered in frosty ice? Or are you seeing ice on the freezer floor?

Can you verify that model # again? I'm not finding it still. I'll look on work computer later, it has better model database.

Just so you have it this is the service manual for a similar unit:

https://drive.google.com/open?id...vj9imrTR6RklJdHVIeTlvQVk

I think it is same for most models of that series. That error starts on pg 36.
It's kinda dense and translation issues are common. Short version is that the main PCB has (or thinks it has) sensed that the unit failed to defrost based on a temp sensor located at the top of the evaporator. When it refers to test modes it means the tiny button located on the main PCB on the back. If you have a multimeter you can run through the checks but in the short term try simply unplugging for 15 minutes and see if error returns in 24-48 hours.

If it actually isn't defrosting you'll have visible frost build up on the rear wall of the freezer in about a week, depending on humidity where you are. At that point airflow behind that panel will be mostly obstructed and temps will rise. Simply allowing it to defrost by unplugging it for 24-36 hours with doors open will temporarily restore cooling but the issue will need to be addressed.