United States Marine Corps Pocket Watch

Gold and silver colors with chain and clasp. Front: "A grateful nation remembers" "1941-1945 World War II 1991-1995" Back: "50th Anniversary of World War II" This clock does not work. It may need a new battery, but I'm not sure how to open the battery compartment, and I don't want to damage it because it's in excellent condition. It would make a good collector's item.