Problem heat pump - supply cold, no hot water: system limit

I have a problem with my heat pump. We have only just bought the house and I am not familiar with it yet. The supply line is ice cold, so no heating is working. Hot water also does not work. It is controlled by a Dimplex heat pump manager. The display shows "System Grenze. Sperre". Normally, it should say something like heat pump on. What could this be? The problem has only appeared recently. Regards, Tobi

Have you ever looked into the [Dimplex] manual? It contains a lot of information about different locks. Without the exact model designation, we can only guess. Is the message on the display really just "System Grenze. Sperre."?

Yes. It says exactly that. If I see correctly, the heating is a LA17TU from Dimplex and in the basement there is a Hydrotower HWK 332 Econ with heat pump manager. I probably have to call the installer. I cannot find it in the manual.

When I enter "Dimplex System Grenze Sperre" into Google, the first three search results already seem to offer quite competent explanations and solutions. Is there really nothing in there?

These are the manuals, but they don't contain anything suitable. Or do you get different search results?