Netgear never made BIOS updates for newer NAS available to the public. My understanding is that the new BIOS also updates the available BIOS options and if you don't also update those, which depend on what version you come from as well as go to, you'll brick the NAS.
When we had technically competent mods for the forum, they'd usually do it for you remotely as a courtesy (but with you understanding it's at your risk). But now, I think you're just out of luck.
Updating the BIOS is not without risk and doing it remotely can involve a few remote sessions (depending which BIOS one is upgrading from and to) with the second one fixing a side effect of the upgrade.
I do recall that some manually changing BIOS settings on the 516 bricked some units, but I left NETGEAR many years ago now. Updating to a newer BIOS is a bit safer, but not without risk.
Attempting to change the BIOS settings or upgrade to a newer BIOS is not supported by NETGEAR, and if it goes wrong can end up with a bricked device.
