That sounds more like a dead battery than anything
Same here. Ive rebuilt more than a few engines and done all sorts of other repairs to numerous cars.. another hobby of mine.
We have a Jeep Grand Cherokee that would do exactly as he is describing, except randomly. 95% of the time the car was fine.. but once in a blue moon you would try to turn the key and get nothing. Or it would try to start, then knock off, then not let you restart.. gauges flickering and moving all over the place, interior lights dimming.. etc. Thought it was the ECU for a while, then I checked the battery terminals. They were shot.. when you had them tight as they would get you could literally wiggle the terminals around. Fixed that... ended up getting a new battery later from trying to crank it over so much. Once a car battery goes dead their never the same when you charge them back up.
My favorite terminals are marine terminals.. theyre cheap as crap, easily disconnect and are much much stronger. They will outlast your car more than likely.
They look like this.
Their what Ive used on all of our cars including mine.