An electronic locking device can be configured to become active from a low power state, receive physical input to unlock, and provide access to a replaceable power supply. An electronic locking device can use a combination of physical input and discovery of an authorized mobile device to enable transition from a locked state to an unlocked state. Authorization can be internally stored or externally obtained through a service. An electronic locking device can match a series of physical interactions to a series of stored interactions to enable transition from a locked state to an unlocked state, when an authorized device is unavailable. An electronic locking device can provide access to a replaceable power supply when a latch is released.