Find geothermal probe again without digging?

Hello everyone,
we bought our house 8 years ago.
Now we might want to build a pool in the garden.
However, we cannot find any reliable documents indicating where the deep borehole for geothermal energy took place.
The previous owner once roughly showed us a spot in the garden. In the documents, it is sketched below the terrace. But really a bad sketch.
These two points are about 8 meters apart. Is there a reliable way to find the probe without digging?

An attempt with a thermal imaging camera might be quite helpful and could lead to success. However, I would preferably do it in the evening at dusk/after sunset to avoid heated surfaces in the search area and reflections. The area must be as "open" as possible, meaning not sealed.

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

I have now contacted the drilling company. Maybe they will find it in their records. It was only 9 years ago.

Drillings must be applied for and the drilling point is specified for this. Something should also be found in the documentation from the drilling company. In NRW, drillings can also be found in Geoportal, I believe. In case you live in NRW

I live in NRW. Where can I find the drillings there? Nothing can be seen on the [Bohrungen] map. Neither mine nor the neighbors' drilling.