All depends on how serious damages are...
Usually I use very thin wires taken from stranded wire (which usually comes in PVC insulation).
Sometimes it is not even needed - small scratches (from screw driver, for example) can be fixed by soldering iron, solder and rosin flux (!) ... yes, rosin flux is very important part here anyway...

I wouldn't trust any "conductive pen" - they are not enough reliable for repaing motherboards and having high enough resistance... For repairing keyboards - yes, but not for motherboards...