They grey pads. There are four of them. VERY carefully peel them with a x-acto knife and place them sticky side UP (they lose their stickiness VERY fast, like after two removals...). The screws are under those...
awww don't worry, I can see how it woudl be easy to make that mistake (I pulle dout my old Intelli Mouse Explorer to look at it when I read the thread).
My new mouse (Microsoft Cordless Blue Intelli Mouse) has the hologram sticker on the battery cover so that mistake can not be made with it...