The easy way would be to
- shut down your Nas
- unplug all hdds
- plug in a blank hdd (can be a small or older model, 250gb for example)
- start up your Nas and do a new installation
- install the updates and check if everything is working
- shut down your Nas again
- unplug the test hdd and plug in your previously used hdds
- start the Nas and install the update