When I opened up my Apple Wireless Mouse to replace the batteries, there was a metallic "strip" inside. I have no idea how it goes back in and it isn't shown in the instructions here. Where does it go?

I have an Apple Wireless Mouse (model A1015 EMC No. 1938).

I metal "strip" fell out. I can not figure out how to put the strip back in.

Leaving it out, the mouse doesn't work (no light, no nothing).

Does the strip actually belong and if so, where does it go?

I went to the Apple site and looked up how to replace the batteries and started off saying to turn off the mouse. I have no idea how to turn off the mouse. It also did not show a metal strip on the inside.

When I opened the mouse, the battery cover popped off. Without the metal strip, the cover does not pop off and is very hard to remove.

HELP!!!