That was my point in post #12, but if he wants to rewire the mouse, then I see no harm done, as implied by @djsfantasi.About the only thing you can do is rewire the cable.
Anyway, I suggest he starts by checking for continuity in the cables, connecting the mm's probes on the extremes of each wire, while gently jigling and yanking them at the same time, to see if one of them is internally broke.