RND4000 Stuck booting; 4, 2TB disks installed; all disk drive LEDs off; power supply fan is running

My RND4000 has 4, 2TB disks and the NAS had 0.2 TB free when I shut it down by holding the power button down for a few seconds. (Had a power failure and manually shut the NAS down before the UPS battery was depleted.)

 

When I started it this morning, I noticed that it stayed in the "Booting, please wait..." state, and that none of the disk LEDs are on. The fan is running, so I'm pretty sure that the power supply is working. Raidar 4.3.8 does not see the device. The first time I ran Raidar, the Windows 7 firewall complained, but I told it to allow Raidar and it certainly behaved differently on all subsequent attempts with Raidar so I don't think that's the problem with Raidar.

 

I have tried the factory reset by holding down the reset button until the LEDs flashed twice (which shows that the LEDs are still good), waited about 6 minutes which should have been more than enough time for the disk test to complete (at which time no error message was displayed on the LCD), and then pulled the plug since I didn't want to wipe out the disks. I tried powering it up again by pressing and releasing the power switch, and am now back in the same "Booting, please wait...) state in which I started the day.

 

I have a backup from last Sunday, so I've only got 5 or 6 days of data at risk, but I'd rather not lose any if possible. The fact that none of the disk LEDs are lit is a concern, but I haven't paid enough attention to what they normally look like during boot to know if that's not normal. The manual says that an off LED means that there's no disk present, but that's not true. I haven't moved the NAS/cables since I turned it off, so I don't think that's the problem. If the hardware isn't broken, I'm wondering if the fact that the disk is so full may have something to do with it, although I don't know what I could do about that since Raidar can't find the device.

 

Since Raidar doesn't work, I don't know the firmware/OS versions, but I don't remember upgrading either of them, although my memory is often imperfect about such things.

 

The NAS is cabled to a 1 GBit/second switch to which my computer and router are also connected. The activity lights on the line to the NAS are flickering, but the NAS is shown as disconnected on the map of my network produced by my router which performs the DHCP function. The NAS has an IP address assigned. 

 

Any advice would be appreciated. Thanks in advance.