The word "brick" is used to reference consumer electronics, describes an electronic device that due to severe a serious misconfiguration, corrupted firmware can no longer function, hence, it is as technologically useful as a brick.
Some devices become "bricked" because the contents of their nonvolatile memory are incorrect and can be "unbricked" using separate hardware (a debug board) that accesses this memory directly. This is similar to the procedure for loading firmware into a new device when the memory is still empty.
This kind of "bricking" and "unbricking" occasionally happens during firmware testing and development. In other cases, software and hardware procedures, often complex, have been developed that have a good chance of unbricking the device. There is no general method; each device is different. There are also user-created modifier programs to use on bricked or partially bricked devices to make them functional.