Well, the NAS would have been streaming data that made the switch appear to fail, but if it actually failed, that's not the NAS. As you say, the switch is fine, so apparently there wasn't a failure there.
If a factory reset doesn't bring it back, it may be toast.
One thing to try if the reset fails, remove both drives (remember which slots they're in), and try powering up. The NAS should power up with no drives, see if you can access it's web setup that way.