This indicates a hard drive failure, your Masterlink will need service. Try these steps to possibly get temporary access to your data. There are no guarantees that this will work, but you might be able to get the drive to work long enough to get your projects off of the drive.

Hold Play & Rec as you power the unit on. If this does not help, you'll need to send the unit in for hard drive replacement.

This can also happen if a newly installed drive has jumper settings that are set incorrectly. Some drives will work better set as "master" and some are best at "cable select."