[Big hammer]

While on vacation my modern was having issues like yours. We where headed up to Rocky Mountain National Park, stopped for gas and no start, wiggling cables got it going. Stopped at a parts store and they checked out the charging system. Replaced the battery and that didn’t help keeping the old battery. Heading up fall river road about to the tree line we all raised the electric windows at the same time :-( and killed the engine. Jumping the battery didn’t help, guessing that the starter I installed two before might be the problem. Started with the starter cable I remember that it went on hard, nut to post. Well if I broke the post the starter was coming off anyway so I turned the nut maybe 1/8 of a turn and bingo no more problems :-). Clean and tight !