You might ensure nothing is inserted into the USB ports. Sometimes a memory stick is left in the USB and it will try to boot off it instead of the system drive. Sorry to hear you didn't keep backups of your files. All points are synced to the other NN3D units. You might disconnect the problem unit and make one of the the other units the master and back up your user data. If this is a single unit, you might have little chance to backup your data now that you have a problem. I would send the unit into the repair center and hope they can do something to recover the data.