LS-Q4.0TL/R5 F/W 1.11 I21 Checking Disk 1 error

[richardbrookeuk]

After many years reliable service, my Linkstation started giving me this error. The disk lights are all green and no checking seems to be taking place since they are 99% inactive. What happened just before was a power outage whilst it was still booting. I read a lot of the previous posts, but wasn't sure how to proceed. Obviously this is out of warranty now, but wondered if there was any Buffalo technical support I could contact?
Other information: RAID 5; Web interface brings up home page and the error messages. NAS Navigator shows the error too. The flashing error lights (2 slow pink, 1 fast pink) can be returned to steady blue, but putting a USB stick in the front. However, this doesn't make the error message on the Web interface go away, nor make the RAID array accessible in any way.
I'm presuming the next steps to retrieve the data would be:
1. Factory reset to default settings (which would not erase the RAID array I understand)
2. Downgrade the firmware to 1.10 (unless there's an upgrade?)
3. Boot using TFTP to see any useful diagnostic messages.

Any help much appreciated.