I am using Pegasus 2 with 4 bays 2 TB each for back up and photography storage. It suddenly became not responsive, is not shown in Finder and I can not switch it off. There was a system message saying that back up failed. Pressing power button on Pegasus does not help, and I am afraid that disconnecting the unit from power may cause malfunctioning. Promise utility also does not start.
How can switch it off or restart?