Some of this information from kuroboxwiki:Brick
In the context of LinkStation hacking to brick a LinkStation means to render the LinkStation unusable. A bricked LinkStation does not boot any more, does not respond to requests (e.g. for serving data via Samba), enters EM Mode, and/or does cyclic reboots.
Effectively, the LinkStation is just a brick, which can only be used as a door stopper.
Fixing a Bricked LS
Re-animating a bricked LS depends on what whent wrong or what was done wrong. Sometimes re-flashing the original or a hacked firmware & OS can help (see Articles/GeneralFirmwareFlash, Articles/GeneralManualFlash. Sometimes it is necessary to physically open the LS, connect the disk to a PC and re-image the drive. See Articles/GeneralRescueGuide for instructions.
Linkstations/Kuroboxes that have been bricked due to bad flash memory contents can be restored by rewriting the flash memory with the correct contents. However, since the device can not be booted, this requires the use of JTAG.