LAN port not working at Netgear RN 102

The only one of those choices that will work is #3 since you didn't set up the backup button.

Have you tried another port on the connecting device?  Is the port in question on a router or a switch?  If the LED on the unit never comes on, even at power-on, then there is likely something wrong with the NIC or the power to it, neither of which is repairable.  A power surge can cause that.  If it comes on and then goes out, and you are plugging it into a "green" switch, try plugging it directly in the router or a computer.  I have a unit where that matters (though I think it's because the unit is on it's last legs).

There are some options for recovery using standard Linux tools and a bootable Linux system, too.  But you need an empty SATA connection or a USB to SATA dock.  The NAS doesn't work like one.

I find it interesting that you say you have another option for backup but apparently weren't using it since you need to recover files hat have no backup.  As you have found, RAID alone is insufficient to insure you don't lose anything.  You probably haven't actually lost anything, though you could have.  You probably just lost access to it without investing some time or money.