ReadyNAS NV+ won't power on

Hello: about 6 months ago during an overnight thunderstorm I powered off my Netgear ReadyNAS NV+ (using Frontview -> Shutdown) and once it had switched off I disconnected it from its UPS and went back to sleep. When I returned to it in the morning it wouldn't power on. There are no signs of life at all, I've tried plugging it in, unplugging it again, plugging it back in, and holding down the front button for different durations - all to no effect.

There were a couple of previous occasions when I'd turned it off and it didn't immediately come back to life when I pressed the front power button - but mysteriously it did turn on by itself, say, 10 minutes later. Or one time when it refused to switch back on until I'd pressed the power button every day for 2 weeks - then it suddenly sprang back into life again.

I've survived without it for 6 months, but I know I'm living on borrowed time. I keep all of my important files on the NV+ (luckily I had copies of the files I really needed on my PC when this all first happened) and I had it running nightly backups to an external hard disk connected to the USB port on the back.

I can't know for certain, but I think the power supply must have failed. There are no bad smells or anything like that (my first generation 1 NV went out that way quite spectacularly some years ago), it seems to have died a quiet death - but perhaps the problem lies elsewhere?

Anyway, I need to know what my options are (assuming the problem is with the power supply). I can't seem to find a replacement PSU anywhere online. Is there any scope for rigging up a regular PC PSU? I remember some threads on this forum discussing this a while back, but it involved complicated rewiring. Otherwise, does anyone else know where I could source a replacement in the UK?

Alternatively, I'd be very glad to hear any suggestions for coaxing the unit back into operation - maybe there are some tricks I'm not aware of at the moment.

Thank you very much in advance for your help!