Do you mean the battery check lever is frozen? If you can move the lever, and nothing happens; check the battery and be sure to clean the battery contacts with a pencil eraser.
Make sure to take the batteries out, clean the little cap that screws the batteries in. Some times those little batteries will leak and make a little layer of film on the cap itself and won't allow for a good contact. Sometimes it takes more than an eraser to get it clean enough. Good luck.