Has the wiring diagram for the boat been used to trace the fault? Can images of the appropriate pages be posted?
My assumption is that there is a contactor that toggles power to the windlass, based on a dash panel enable switch and that there are up/down contols, at the helm and at the bow, in-addition to the previously-mentioned circuit breaker. Is that all correct?
If all correct, when the dash enable switch is toggled, then does the contactor change state to provide power to the windlass?
There is probably a windlass controller near the windlass, correct? Does it have appropriate power? What model windlass?