What is this?

My boiler stopped working recently and I've been trying to figure out why. From what I can tell the power from the thermostat to the control box is working, as well as the power to whatever this thing is, but I have no clue what this is. Could this thing cause a boiler not to fire up? While I was doing testing I cycled off my boiler and when I turned it back on whatever this device was rotated 90 degrees. Originally the metal bar was vertical instead of horizontal. What does either direction mean? I'll probably have to get this boiler replaced since it's extremely old, but would be nice if I could get it to fire up until I can get someone out.

https://preview.redd.it/jj0oscnxhqyf1.jpg?width=4080&format=pjpg&auto=webp&s=9c3f5dcf9ad6c09adbc8ddafa653fffd131ef19f

https://preview.redd.it/98378fnxhqyf1.jpg?width=4080&format=pjpg&auto=webp&s=ff80edac708124c0c63bcd10c79ff0efe021d985