Hi, its now 2020. Im already trying most of your posting or discussing in this group but it was never solved my problem. My WD Sentinel DX4000 was displayed “Startup Failed: 0xD9” at screen.
First, i think maybe it was hard disk error. But after checking, everything ok.
if you need your data you need to Google for raid recovery software.
If you just want to rebuild the box you will need to place each drive one by one in a usb adapter/caddy on a worker pc and do fdsik>clean on them. Then do the recovery process
No clue, it just seems to happen sometimes. But if you used to have 4 blue lights and now only have 3, it may be a hardware issue. Bad drive or bad bay