2004 GMC Sierra 1500 won't turn over, despite new battery

[Dane45]

2004 GMC Sierra 1500 195,000 miles on it. Has a new battery but there are times when it won’t turnover. Usually I can wait 5 - 30 minutes then it starts. Today I had everything off but my driver door open and my inside lights came on and off. I also tried to start it and my horn would make a soft honk (if that’s the word for it going off) HELP!!! took it to shop they tighten things up and nothing. HELP!!!

[Tester]

The first thing you want to do is remove the side mount positive battery cable bolt to see if it looks like this.

Then you want to look at the cable itself to see if it looks like this.

If you see any of this, replace the positive battery cable assembly

Tester