Had clicking with no start

It may seem overly obvious but are you sure you have all the wires attached to the starter? Sometimes the easiest things are often overlooked.

First thing to check is if you have voltage to the stater.There are two wires on the starter check them with a test light or a voltmeter.you should have power to the big wire always and the smaller wire should have power when the ignition switch (key) is in the start mode.No power on big wire check battery connection and condition of wire from battery to starter replace if needed.No power to smaller wire check starter relay and fuses also GM ignition switches are known to have intermittent starting issues and switches locking up.