Hot water heater furnace not shutting off

[JeffAndPam]

I admitted my mistake. When I tested after putting that on there, I realized I did need to seek advice from others. That's why I value the insight of people here. Posting that picture helped me learn.

BTW, doing more testing and digging around more, I found a potentially faulty thermal cutoff:
View attachment 21938

It had some corrosion on the end. Since they are cheap enough, I've ordered a new one and will test again when that arrives.

UPDATE: I have fixed my boiler. It was indeed the faulty thermal cutoff. This has been replace, and now the boiler works perfectly fine:

Now on to my other issues (there's a list!)