If a spontaneous watch reset to original factory settings occurs, there is no backlight or a dim display, please replace the battery.
The expected life of the battery is approximately eight months, based on typical use. If the watch is used to time a short duration (or left running) on the repeat function with vibrating alert, then the battery life will be significantly shorter due to the higher battery requirements for vibration.
WARNING! INGESTION HAZARD: This product contains a button cell or coin battery.