Ryan falcon

Having similar issues with my 2016 gmc Denali xl. Working fine, traveled about 1.5 hours away and stayed off for about 4 hours. Get back in and push to start doesn’t start. Just clicks one click. Mechanic stated a wire connecting to starter was disconnected because connector piece broke off. Spliced the wire and connected it really good to starter. Still doesn’t start and is now chattering. Battery and alternator tested fine. Changed the starter. Still didnt work. I was able to wiggle the ignition relay and get it to hesitate to jump. Changed out the relay. Still didn’t work. Changed out the fuse box. Began to work and drove it to my job. Got off my job and tried to start it and it wouldn’t work. Took a few more tries and it started. Drove it straight to mechanic. Stopped it at the mechanic and attempted to restart it…one click and didn’t restart. He checked all wires, fuse harness, and all grounds..everything looked fine. He noticed a wire on the positive battery loose..tightened it. It started right up. He ran it on and off for two days and drove it around with no problems. I pick it up from mechanic shop and drive it home. Turn it off in my driveway and say let my try and restart it just to see……..DOESN’T start! One click. Try a few more times and it eventually starts. Try turning it off and on multiple times it starts every time. I just don’t know and don’t want to get stranded somewhere. Maybe the starter is a bad starter. Maybe I need to change the wire from the positive part of the battery.