After a few years of service, my ReadyNAS NV+ broke one day. The hardware was fine, but the software had painted itself into a corner and didn't want to boot at all.
Googling showed that lots of other people have been bitten by the same bug. I phoned support. The support person told me that my box was out of warranty, and would I please post to a web forum and
I'm sure someone will help you. I could tell from his voice that he didn't really believe that.
I eventually moved the drives to a linux box. LVM (on ubuntu 10.04) recognised the drives automagically and ext3 let me mount the file system, so I bought a new Synology NAS and copied the data to it.
When I did a factory reinstallation (the hard way) the ReadyNAS booted without problems. From now on I'll use it to back up other devices, nothing more.