My first thought is to try to narrow down where the issue could possibly be. Maybe disconnect all but the one furthest away from the spot on the floor. If it still beeps when you walk there, try disconnecting that one and connecting the second-furthest.
(Of course, if they’re daisy-chained, you might not be able to connect them independently. But if you can, it could help.)
Any wiring that could possibly run through the area where the spot on the floor is, disconnect it and try the spot on the floor again.
Do that until you’ve got it narrowed down to “the connection between point A here and point B there.” Confirm that if the entire system is fully connected except for that wire, it doesn’t go off.
Then try disconnecting just one end. Then the other.
Then, disconnect both ends and break out your multimeter with a continuity detector. Connect two wires in that suspect cable that shoudln’t be connected and walk over the spot on the floor. (Go slow, because some continuity detectors take the better part of a second to detect and start beeping.)
Theoretically, that whole process should help you narrow down where exactly the problem is before you start tearing up floorboards or whatever.
Also, if you do narrow it down, you might be able to get away with tying a new replacement wire to the old wire and pulling it through, which would be a lot less invasive if you do manage to pull it off.
Though, if the issue is a nail through the wire or something, your best option might be to just open a hole in the floor right under “the spot” on the floor.