You've been within the same range, so I think that it's probably a recent problem.
I would buy a new battery or scale immediately since you are such a slave to the scale

You are SO close to your goal weight, I think you can make it by March 1st. But if you start drinking regularly again, I don't think you will, Bizi
If you drink for one day, I don't think it will be a big deal tho. It would be like a cheat day if you decide to do that.