Unable to perform a Boot Recovery using a USB flash device

You need to do it as the 'root' user
Try
# sudo dd ...

Why are you wanting to do a USB Boot Recovery in the first place? This may be unnecessary

Thanks for your reply, I'll try that.

I'm getting an ERR:bad FW -message and the NV+ is stuck on boot phase. I've tried OS re-install without any luck.

The # sudo dd ... command doesn't give the "permission denied" answer but it doesn't seem to do anything else either. I've waited for 30 minutes without anything happening. Surely it can't take that long?

What exactly did you enter? When I wrote "..." I meant for you to write what you did originally.

e.g.

sudo dd if=source of=destination

If using Mac OS X you can drag and drop the source to the Terminal to fill in the path for "if". You can look up in Disk Utility which disk your USB key is e.g. /dev/disk1

I wrote:
#sudo Dd if=/Users/my_username/Downloads/ReadyNAS_USB_Flash_Recovery-4.1.10.img of=/dev/disk3

I used drag and drop for the source and tried both disk 3 and disk3s1.

Make sure disk3 is unmounted before you try this command. Also it is "dd" not "Dd"

Thanks for helping, but no luck so far.

#sudo dd if=/Users/my_username/Downloads/ReadyNAS_USB_Flash_Recovery-4.1.10.img of=/dev/disk3 doesn't do anything. In disk utility the only partion in the usb is unmounted and the only option is to eject the whole usb.

The "#" would comment out the line. You aren't typing that in the Terminal are you?

That was it!

I was able to do the usb boot and os reinstall but the problem remains. I'm out of ideas, I think I have to try to contact technical support.