How can I repair a ground-fault?
The best thing to do is replace the defective wiring. Disconnect the load side of the GFCI and at all downstream junctions. Then check for neutral/ground continuity on each segment of the wiring. Once you locate the segment that shows continuity, search for a short location inside the junction box, and failing that, replace that part of the circuit.

Short of that, depending on your situation, you may not need to wire the following outlets to the GFCI load (e.g. if they are not in the bathroom). You could pigtail the load connection to the line side of the GFCI so that the downstream devices are not protected. If they need protection, they can each have their own GFCI installed, again, only wiring to the line side of the GFCI.