RN10222D Power Light (blue) Slowly Flashing

I was working on the web console of my NAS and it reported the lastest firmware was available, once I had finished my changes I downloaded and start the upgrade, that was my biggest mistake!  Knowing how long these updates take, I left the unit over night and went to access the following day, found I was unable to access my shares and then noticed the power light was flashing slowly.  Turned the unit off and then back on and left for a further day, blue light still flashing!

I have since tried to access the boot menu using the reset button however this option is not available using the backup button, I have tried os reinstall and volume read, all I get is the blue flashing light.  I have removed the disks and tried to gain access to the boot menu and again not available just the blue flashing light.

I have a backup of the data as I know how fragile these "Netgear business NAS" drives are, just did not want to have to complete a full reset and go through all the hassle to rebuild, any help would be much appreciated as I have run out of ideas.

Perhaps Netgear should test their firmware updates to destruction before releasing them to Joe public, as this is the second time a firmware update has upset my NAS!