My bro has a 91 maxima.. VG30E 5 spd

I replaced the starter, the battery, checked the starter fuse, checked the clutch safety switch, everything works.. turn key to start.. relay clicking by the fuse pannel, but thats it.. nothing.

he said sometime that he had someone jump him and it started fine, led me to think it was a bad ground.. cant find anything.. suggestions? I only have a crappy chiltons manual with no starter system wiring diagrams to go off of..

 

my car does that when the wires aren't tightened down on the battery terminal.