Data Recovery on a RN528 with X-Raid configuration

Do you see any activity, even brief, other than the Ethernet, when you plug it in?

I do not have, nor have I ever seen except in photos, a 528.  But, because it's a necessity to support WoL, I can tell you that the Ethernet ports run off of "standby" power (which is either 3.3V or 5V, depending on the design).  It would be typical of a unit with an internal power supply (that typically has a 5VSB output) to use 5V.  But the main thing here is that the StandBy voltage is always on and provided by a circuit independent of the rest.  So, a power supply or on/off control issue could be your problem.  But something elsewhere shorting out one of the voltages might be it as well. 

Most OS6 native ReadyNAS with internal supplies use a modified Flex ATX supply.  The modification is removal of the negative voltages from the connector and putting more 12V in their place.  I would expect the 528 to use a modified (or perhaps unmodified) Flex ATX12V (with the 24-pin connector) rather than an older basic Flex ATX (with a 20-pin connector).

Now, before you do anything else, you really need to pursue all avenues of getting warranty support.  Once you open the unit, Netgear will certainly refuse to honor the warranty.  Of course, if you know you aren't covered (you bought it used, for example), then no need.

If you decide to try something on your own, and it is a modified or unmodified Flex ATX(12V) supply, the first thing to do is to remove the power supply and try the "paper clip test", where you ground the power-on pin and see if the supply comes on (Green wire to any black wire).  That way, you can determine if the on/off circuit of the NAS is the problem.  While it's on from the jumper, you can also check the output voltages with a meter, but doing so without a load isn't a definitive test (no output says it's bad, but seemingly good output might not stay so under load).

If the NAS On/off control is the problem, a quick solution is to permanently jumper the green wire to black, bypassing the power control.  That means the unit will come on when plugged in and not turn off when commanded to do so.  But the power-off command will put the NAS at a point it can be safely unplugged.  You could investigate whether it's just a button issue, but most ReadyNAS use a double-pole switch to provide redundancy, so that's unlikely.  Without a schematic, the rest is basically unrepairable.

Since I'm unsure of the type of supply, I don't want to give any advise past that.  Let me know the number of pins on the output connector and if there is a blue or white wire or any unpopulated pins and I'll be able to see if it's like most other ReadyNAS use. 

How many drives are installed in your NAS, and was it using RAID5 or RAID6?  I ask because it will determine what other ReadyNAS you might potentially use to recover your data if it comes down to to recovery because the unit is unrepairable and Netgear won't replace it.  Replacing with another 528 is likely going to be tough.