I believe I have the XS. It was a while back, it gave me an error code (8 maybe) and I did what the book says to do. I think that was to take out the batteries and put them back in (?). Whatever it was, it didn't work, and the book said to call Roche, which I did. The Roche lady told me it was either the batteries or the meter. I believe she had me do the take out and put back in scenario again. Didn't work. She then told me to replace the batteries with newly purchased ones (with the same brand that they came with if possible). I told her that the machine said the batteries still had power. She told me again to replace the batteries with new ones, preferably the same brand. I did and it worked fine afterward. In the little book I have for INR recording, I recorded when I replaced them.Interesting, are you meaning the XS? How have you determined this?