Car won't turn over. All power. Battery starter and alternator test good. Jump not

I HAD THIS PROBLEM WITH MY CAR FOR A FEW YEARS. I WAS LEFT STRANDED MANY TIMES BECAUSE OF THIS EXACT SAME THING HAPPENING. A GM DEALER KEPT MY CAR FOR OVER A MONTH AND FINALLY FOUND THE PROBLEM TO BE A DEFECTIVE ONSTAR MODULE. PULL OUT THE FUSE FOR YOUR ONSTAR AND LEAVE IT OUT. SEE IF THIS FIXES YOUR PROBLEM. IT FIXED MINE. I HAVEN'T HAD IT HAPPEN AGAIN IN 2 YEARS.