Broke my water pump bolt. Now what? (Update - broken bolt is out)

Being accessible opens up a lot more options. Lots of great ideas here. Pretty much all of them involve heating the part to loosen it up.

As I am a tool accumulator / hoarder, I tend to like options that involve getting new tools.

My first thought would be to buy a Harbor freight $100 mig welder. They plug into 110v and don’t need a bottle of gas. Gotta buy a helmet too. Watch a few you tube videos, Round up a bunch of leftover bolts & nuts & weld them up. You will be surprised how easy it is. Opens up a whole new world of metal projects.