You noted this as well upthread, and I may be wrong, but I think that the GOP delegates are, in fact, obligated to vote for their pledged candidate on the first ballot. And since virtually all delegates are pledged to Trump, there won’t be a second ballot.
In 2016, the party couldn’t quite coalesce around anybody else, and as improbable at it seemed, Trump began to pick up momentum, and ended up being the nominee. From all outward appearances, “it all just sort of happened”. I went to bed election night just assuming that Hillary was on her way to victory. I woke up in the middle of the night to tend to natural circumstances, checked my smartphone, and sure enough, “President-elect Trump”. Not what I was expecting.