Hello. I have a 2010 HHR and one day it just wouldn't crank or start. I'm not sure if it's related but a few weeks before this happened the ac would intermittently shut off and if we smacked the dashboard it would come back on lol. The battery is good we changed the crank relay under the hood and the one for the ac inside the car. The dash lights do work and I feel like I hear a click that seems like it come from the inside fuse panel maybe? when I turn the key. I don't have a meter available I just wanted to get some ideas? Thank you

 

Find a meter and find out what the battery voltage is. Should be more than 12.4 volts. That should have been the first thing.
Second : look at the connections on the outside of the under hood fuse box, make sure the front one is tight.
Third : Tighten the 4 bolts inside the under hood fuse box tighter than "afraid something will strip".

 

Need to start at the switch.
This is strange.
"I feel like I hear a click that seems like it come from the inside fuse panel maybe?"
What?
Get your meter and report back. Battery needs to be good, not might be good.