Fossil AM 3688 Wrist Watch "4154" Questions

I have the Fossil FS-4154, Arkitekt and have recently tried to change the battery. Now when I try to replace the backing, the screen goes blank. I don't know why? Did you put the protective cover back

I have the FOSSIL GRIMM fs-4154 250611. I have managed to get the back off and lose the battery. But before that a jeweler had tried to fix it and said it was damaged. When I brought it in, however, ...