Readynas duo hangs after startup

This morning my ReadyNAS Duo did not start up. Two green lights for HD on but the blue button did not light up. Raidar could not see the duo and pressing the blue button for 5 sek. could not stop the duo. Only way to stop it was to take power off. After starting up the RAIDar could see the duo and said "rescanning disks" for 15 sek. and then again it could not see the duo anymore. Pressing RESCAN just gives me the help screen. I cannot stop the due by pressing the blue light for 5 sek. Wondering if I can reset the duo without loosing what is on the disks. Anyone?