Hello- My comment is many watches are water resistant. Therefore your watch should of been sent out to insure it's water resistance. Once case back of a watch is opened, you have broken the seal. Or it needed a new gasket to keep mositure out. The most important is the gaskets, or 0 rings-made of rubber, nylon or Teflon which form watertight seals at the joints where the crystal, case back and crown meet the watch case. if the watch is a chronograph, the chronograph pushers will also have gaskets. . A screw-in case back, as opposed to one that pushes in, also contributes to a watch's water resistance. A screw-in crown, a feature of many divers' watches, helps prevent water getting into the case through the watch-stem hole. When it is screwed down it forms a water tight seal much like the seal between a jar and its lid. It is not recommended to wear your water resistant watch in a hot shower, sauna or hot tub. The extreme heat causes the metal parts to expand at a different rate than the rubber gaskets. This creates small openings that can allow water droplets to penetrate the watch. Sudden temperature changes are especially harsh. Take care not to jump into a cold pool after wearing your watch in the hot tub. The person who changed the battery should of let you know that he/she can not guarantee the water resistance of watch after case back is opened.
