For Future searchers...
First off I have only registered to post up something helpful for future generations :-P
Back story:
After a brief powercut/surge/whatever, my terastation Pro 2 HD-H2.0tgl/R5 took ages to boot...loading kernel... after about 5-7 minutes, it failed with System Error E04 - Can't load Kernel.
All round the houses:
I was scared to touch anything incase I lost my raid. So I took images of each disk and set about trying to reconstruct my raid outside of the NAS box.
It took me nearly 24 hours to image each disk (to a compressed file in R-Studio) 4x 2TB WD20EURS Green's.
Once I had the images, I felt I could play around a little while leaving R-studio to do it's thing.
RE: Raid recovery. I have given up but that's another story.
Summary & possible fix for others with E04 error:
Discounting all the time I spent messing around, I have summarised what I think brought my raid back online and allowed me to access the data.
Remove All 4 disks out of the terastation (image them to safe guard you).
Remove power
Press power button to drain the capacitors.
Put the power cable back in.
Open the drive door and press and hold the button under the LCD screen (looks like a fairly standard factory default button.
The NAS should boot into EM Mode.
Once it announces it has an IP of 192.168.11.150, Press and hold the power button for 8-10 seconds, until the unit powers off.
Remove power cable. and press the power button to drain excess power.
Add the disks back in (make sure they are in the same order).
Plug in the power cable and press the power button.
Sacrifice a live chicken.
What should happen is the NAS comes back up with RAID5 intact as if nothing had ever happened...You should feel an air of smugness from the NAS.
Caveats:
During my playing around I bought another HD-h2.0TGL/R5 with 4x 500GB disks in it. I took these 4 disks and variously tried them in my NAS (before and after the reset button). It is possible that the info on them was transferred to the NAS as part of the boot up. I cannot confirm/deny. all I know is it booted with Disk 1 in place but complained of the other disks being missing.
The power off, remove power cable etc may not be neccesary but I did it anyway.
Other useful info:
Here is a bunch of info that I found that might help future searchers sort out their specific problem:
http://www.arnebrodowski.de/blog/recovering-data-from-broken-terastation-pro-2.htmlhttp://buffalo.nas-central.org/wiki/Revive_your_arm9_box_from_scratch#Terastation_Pro_v2.2C_Terastation_Livehttp://forums.buffalotech.com/index.php?topic=3064.0https://raid.wiki.kernel.org/index.php/RAID_setup#Saving_your_RAID_configuration_.282011.29The Raid5 is apparently a linux based RAID5.
Big Endians or something.
R-studio has problems detecting RAID5 parameters. It will find a config with 15.7% confidence if you do just the data partitions, but it won't then let you scan the virtual raid. you have to change one of the parameters in order to scan it, but then your data is er...not right. Restore large photo files to test.
I hope someone finds this drivel useful one day