Got my watch fixed. Spent a week and about 75USD.
I know casio's gshock is very tough.It already amazed me when I found the core is still functional after a great crash. I spent two weeks to regain my ability to walk, and until last week my last wound was healed.
Now I'm amazed again by its toughness. There is a huge crack in the front glass, across both XZ plane and Y axis. I assume the front glass is fragile, but guess what? I pushed on it and it still holds! This huge crack even failed to penetrate the whole glass! The inner side of the glass is still one piece.
With additional 2 backups, I guess it's a lifetime guarantee.