I recently bought 3 of the Snark clip-on tuners. And none worked with new batteries. Being inquisitive and not wanting the hassle of returning I investigated. Turns out the battery contact that is mounted on the circuit board is a small disc with two "ears" stamped into it - the ears needs to be sticking up maybe 2mm to contact the battery and these were pretty much flat. Maybe they missed a step in the manufacturing process. Anywho... Easy fix: 1.Pull out lithium battery "Drawer" - one small phillps screw is showing - pull that. 2. Unsnap front from back - there is a locking/snap point about opposite the screw. 3. Bend little "ears" up - little danger of going too far. 4.Reverse steps and it's a great little tuner.