Various prior art locks exist that can be opened in two ways. For example, U.S. Pat. Nos. 3,241,344; 5,148,691 and 6,012,310 describe locks that are capable of being opened either using a key or in a keyless manner.
One keyless manner to open a lock is via the presentation of an electronic credential. For example, providing a lock that can be unlocked by entering an appropriate key code allows a door to be unlocked by individuals having knowledge of the key code without having to provide keys to all such individuals. Providing a lock that can be opened either using a key or upon the presentation of an appropriate electronic credential can be advantageous in that the lock may still be unlockable even in the event of a power failure.