When the front led doesn't turn red, the reset won't work, as the reset condition isn't detected by the firmware. That is at least true for the 'reset without data loss'.
And about the 'reset with data loss', well, I wonder if this is supposed to work on all 5big2's. Normally a Lacie has it's firmware on disk, so when you remove the disks it cannot boot anymore. Yet the 5big2 is sold with and without disks. The diskless version is sold as 5Big Network 2 Diskless
, and is actually a different box
than the '5Big 2 with disks', it has some extra flash memory to be able to boot without disks, and to initialize disks.
Yet that article doesn't say it only works for a Diskless.
I still think one of the disks is (almost) dead, in a way it disturbs the normal fault detection and correction process. You can try to boot it on 4 disks, and leave out another one each time, until it boots.
If the box is still under warranty, it is a good idea to contact Lacie.