I replaced my radiator not that long ago but I don’t have a step by step. I definitely recommend removing the front plastic bumper cover. It makes accessibility so much easier.
Yea that sucks. Do you have a 12mm line wrench? Maybe gets a better grip on that nut? You can’t really hammer on a smaller socket at that angle.
Otherwise trying to break that nut with a dremel/air hammer something to come squarely at it...
Honestly that bolt may have been the s***tiest part of the whole process. I didn’t do any prep for reinstalling the intake - just laid the manifold down and then started working the bolts. I couldn’t remember the socket/extension combo I used...