If a disk drive fails, the Disk Status LED will turn to RED.
Replace the failed disk drive with a new disk drive of the same or slightly greater capacity. Please 
make sure you have powered down the unit.

Step 1: Open the unit's front cover.
Step 2: Pull out the failed disk drive.
Step 3: Install a new disk drive into the slot.
Step 4: Go to Menu -> system to format new hard disk