Help w/truck “acting” dead

[jorswift]

I’ve searched this forum, another and tried YouTube, but still at odds.  
 

My truck 2015 Sierra 1500 4x4.  Went to start it last year and acted dead. But charger on it and it started. Went to store and got new battery. Problems went away. Fast forward to now, 1 year later, truck doing the same thing.  Acts dead, but all lights, etc work, no crank just a click. 
 

I went to auto zone and asked if they can test battery under load, they said it was good and fully charged. But I don’t have much faith in them as we did the same with my buddy truck and he needed new batteries! 
 

Today took off tire and under wheel well. Cleaned all grounds. Tried my best to clean the terminals on the started while it is still attached.

 

 Put all connections back and it started. Pulled the key out to try and again and no start.  So wiggled the Neg cables and bam, started.  
 

Is it possible the cables are no good? Cables look good. I cut the boot off the end and looks good. I’m at odds? 

[mikeyk101]

Yes, quite possible.

 

Make sure to read the post on page 2 by Dick Lichon. It could possibly be the negative post on your battery...

Edited October 17, 2022 by mikeyk101

[jorswift]

Well, tried to clean up all ground that I could find; frame, firewall, block.  Even added a new ground from battery to the frame.  No bueno.  Checked all fuses and relays, all checked.  Charged battery.  Still no start.  Tried to jump the starter with a jumper wire and it did not turn.  So going to to try a new starter. 

[mikeyk101]

What about the negative battery post itself or that negative battery cable? And when you tried jumping, did you attach the negative jumper cable to the engine block?