I recently acquired a TW-7000, which comes with the 548 module found in a few other Casio watches (like the DW-3000). Unfortunately, no battery was installed, and the unusual plus-sign shaped battery clip was loose inside. I was able to position a new battery in place, but securing the battery clip presented further challenges. I couldn't find a workable way to properly secure the two clip ends, despite thoroughly checking out the back of the module with a magnifier. One position half-worked, but it wasn't totally centered, allowing the battery to slip out. Either there's a necessary piece missing, or Casio made the clip anchor points unreasonably camouflaged.
Does anyone here have a photo of the 548 module showing the battery clip installed? At least if I know what the proper orientation is, I should be able to figure this out... of course, I'm assuming Casio didn't make multiple versions of the 548!