Sparc: You'll need to download the latest USB boot recovery image: RAIDiator-4.1.12 and write that image to the USB flash device. To write the image on a Windows PC, you'll need to use Rawrite32.zip. Make sure to click the Eject button after the write is complete. On Macs and Linux systems, you'll need to use the 'dd' command to write the image to the flash device.
Power down the ReadyNAS, insert the USB flash device, and depress the power button on the front for approximately 20 secs – you'll see all the disk LEDs blink once at 5 secs, 10 secs, 15 secs, and 20 secs. Release the button right after the 4th blink. This will start the USB boot recovery process. Once the fan and the lights shut off and the lcd screen displays “Attemp”, press the power button and the unit will boot up normally.
Note: ReadyNAS boot loader does not support USB flash drives with USB hub built-in, if RAIDar does not detect NAS after 5 minutes, please try other brand/model USB flash drives or you can check if the flash drive has built-in hub using Windows device manager.
x86: The procedure is described here: Unofficial ReadyNAS USB recovery guide for NVX/Pro/2100
Note: The USB boot recovery method is only recommended for Sparc systems. Do not attempt this on x86 systems unless advised to do so by Technical Support. Unnecessary use of this can cause problems.