Now must of GM vehicles has this terminal called Remote Positive Terminal. If you trace the red + cable from the battery, you will find that mostly it is connected to some kind of bolt and held down by a nut. It is usually located on the side of the of the engine bay. Tighten that nut down and that should fix no start/crank problem. You might still have lights and accessories because the nut might be loose enough for low amp accessories to work but loose enough when high amp is required like starting the engine.