Find location of wire break in low voltage wire buried in garden grass
There are dedicated devices for that purpose.
I own a Fluke 2042 :

The right device is an RF emitter that you connects to your buried cable.
The left one is a detector that displays the strength of the detected signal.
It needs a little practice, but I am very confident that you could easily follow the buried cable and find out when the signal disappears. As shown in a picture of the user manual :

I found mine second hand on a well known auction site.