If new batteries don't work either, clean the battery contacts in the handle's battery compartment with a cotton swab dipped in isopropyl rubbing alcohol. Clean both ends: deep inside the handle as well as the closure cap. After the alcohol swabbing, use the dry end of the cotton swab to remove any excess moisture from all battery contacts. Reinsert the batteries according to the instructions, and replace the cap. Even if there is no visible sign of corrosion inside the handle, there still may be a film on the contacts that cannot be seen, which may be hindering the power supply from the batteries.