It is highly recommended that you contact a watch repair professional who can perform a watch battery replacement without damaging your watch. Simply opening a watch case can cause damage if handled improperly. For example, some watches have cases that twist, while others snap to open. Opening the cases of luxury watches also requires specially-designed tools. Water-resistant watches, especially, should only be opened and re-sealed by trained watch makers with the correct tools and testing equipment.
When considering watch battery replacement, you must use the exact type battery in the same position as the prior battery. Polarity markings must also be observed. If a wristwatch has two batteries and only one battery is dead, both batteries should be replaced. White powder or liquid in the battery compartment can be a sign of previous battery leakage which may have damaged the movement.
As of January 1, 2012, some states in the U.S. will require the use of only 0% mercury button-cell batteries. Old batteries should be properly recycled to avoid mercury contamination to the environment.