Someone might have lifted a pad trying to put a battery in or take one out (I can't tell precisely but it looks like the D2C15 screen printing is missing part of the C, could be nothing but I see that sometimes if enough trace has been lifted). Depending upon what has been ripped off the fix could be as simple as finding an alternative spot to solder a wire to, or it could be a nightmare involving you having to remake a junction or something.
Just pulled apart mine and there does appear to be a via to the other side of the board next to the battery so you might then have to get a wire to that side somehow, fortunately it only appears to be a dual layer/double sided board. I don't know if it also goes to that top row of components at this point.