Sounds to me like he cut a trench in his concrete deck near the pool and he found a wire from the steel frame of the pool.It needs to be bonded to the rebar in the concrete slab around the pool. Dirt don't matter the concrete is in contact with the dirt and concrete conducts. Tie to the rebar in the slab.
You need a minimum of 4 points around the pool connected to the bonding grid. Code states "The bonding grid must comply with (a) or (b) and be attached to the conductive pool reinforcing steel at a minimum of four points uniformly spaced around the perimeter of the walls of a pool, outdoor spa, or outdoor hot tub." If you do not have 4 points uniformly spaced then they need to be installed.
Could this be the issue maybe time will tell.
Boy I hope this is the fix because that's an expensive maybe..
Edit: Wait, just looked and it says you have a vinyl pool. I assumed when you said wall you were talking about the pool wall. If not the pool wall then what wall? Is there concrete behind the vinyl?