Now's the time to buy a cheap multi meter. Remove the fuses, and with meter set at ohms, prove that the fuses are ok. Then set the meter at dc volts and from one side of the fuse holder to ground (bike frame) you should get a reading, to prove that there's power to the fuses. If that's ok, then disconnect any connectors, and with meter set at ohms, check each wire in turn for continuity. (look for the colours of the wires at each end of the test run, and it's colour to colour) A long job, but now it's the only way of finding the break.
