Sorry, not too too much to add here other than a related story.
A year ago, I painted the basement ceiling with an oil based ceiling paint. The fumes blew out the sensor in our tank as well, also on a Sunday. I tried all the resets, etc. to no avail. Called our plumber hoping he'd have the part, but didn't. He unfortunately wasn't able to get it till the following business day, but at least that's all the time we did have to wait. Like a $5 part too or some damn thing if not mistaken, but I had to work the next day so left it up to him to get and replace.. a hundred or so dollars later.
Bottom line, we couldn't find the five dollar part on a Sunday so it cost me over a hundred bucks on a Monday.