ReadyNAS RND2000 V2 Flashing Power button

Hi all.  My wife accidentally powered down my ReadyNAS Duo V2 the other day and when I plugged it back in and powered it back on the power light is flashing blue and I am unable to access the NAS Drives. The power light flashes 4 time and then stops for a coouple of seconds and then repeats the same pattern. I checked in RAIDarbut it cannot locate the drives.  I looked at the light indicator legend in RAIDar and it says that a flashing blue light means that there is a lengthy background task in progress but it doesn't indicate of the blue light is the power light or the HDD LEDs.  Based on this I have left the ReadyNAS over night but it is now almost 12 hours later and the power light is still flashing in the same pattern.  It has 2 x 2TB drives installed which have about 600GB spare.  Is it doing some sort of background data integrity check or repair?  If so does the length of this task depend on the amount of data stored on the drives?  Many thanks for any advice.