Electronic key for a security system with a mechanism to loosen a battery compartment cover

The key (50) has a housing (10), and an electronic circuit (11) for wireless communication with a security system (70) and arranged in the housing. A retaining receptacle (12) is formed in the housing, and an energy storage (13) for supplying electrical energy to the circuit is arranged in the receptacle. A cover (20) is detachably fastened to the housing, and closes the receptacle in a sealing manner. A retainer is formed in the housing for accommodating a mechanical key (40). A releasing mechanism is arranged in the retainer such that the mechanism is operated by movement of the key. The retainer is formed as a channel or chamber. An independent claim is also included for a method for releasing a cover of an electronic key.