ᐅ Locating a geothermal probe without digging?

Hello everyone,
we bought our house 8 years ago.
Now we are considering building a pool in the garden.
However, we cannot find any reliable documentation about the exact location of the deep borehole for the geothermal system.
The previous owner roughly showed us a spot in the garden. In the documents, it is sketched below the terrace. But it’s really a poor sketch.
These two points are about 8m (26 feet) apart. Is there a reliable way to locate the probe without digging?

A test using a thermal imaging camera might be quite helpful and could lead to success. However, I would recommend doing this preferably in the evening during twilight or after sunset to avoid heated surfaces in the target area and reflections. The surface should also be as "open" as possible, meaning not covered or sealed.

By the way, ideally, the first drill hole should be found in a straight line from the wall penetration of the brine pipe into the basement.

I have now contacted the drilling company. Maybe they can find it in their records. After all, it was only 9 years ago.

Drilling permits must be applied for, and the exact drilling location must be specified. The documentation from the drilling company should also contain relevant information.
In North Rhine-Westphalia (NRW), drilling points can also be found in the geoportal, I believe. This applies if you live in NRW.

I live in North Rhine-Westphalia. Where can I find the boreholes there? There is nothing visible on the borehole map. Neither mine nor my neighbors’ boreholes.