I have also pressed the RESET button on the back of the NAS until it beeped then started it again
How did you restart it? If you powercycled it, and didn't wait long enough before pulling the plug, the reset wasn't applied yet. The box starts resetting when you release the reset button.
Further, AFAIK a 'single beep' reset resets the admin password. For a full factory reset you should keep the reset button pressed until it has beeped three times. Then release the button, wait a minute, and press the power button to shut it down, if it didn't reboot automatically.