S730 lens in extended position camera not working

The problem you describe is frequently battery related. Make sure that you have the correct battery type installed, and that the batteries are fresh/fully charged. If the problem persists, you may have corrosion on the battery contacts inside that camera that is preventing full battery power from flowing into the camera. Remove the batteries and wipe the inside camera contacts firmly with a dry cloth (heavy corrosion may require cleaning with a wire brush, steel wool, or sand paper). Remove any residue that may have fallen into the battery compartment during cleaning, then wipe both ends of the batteries and reinstall them in the camera. This cleaning solves the problem about 90% of the time, and I hope it works for you.