There are few programs to help you with ReadyNASes of late. This is because of BTRFS filesystem used by NETGEAR.
This happens to be an example case
Readynas Ultra 4 Plus – I think the Data is okay, but the Readynas is not functioning. After attempting all official methods to revive a Netgear RN-102ND NAS, I’ve removed the single WD 3TB Green drive to recover its data. Slaving it to a Windows PC, I open a popular program around here called Sysinternals Linux Reader for recovery. However…a dialogue appears stating “can’t open disk: Btrfs Volume 1 (0e34c953:data, raid) Check the disk and try again”.
Sysinternals Linux Reader does not know BTRFS. Furthermore, readers are not very good in reading damaged filesystem. By the time all official methods were attempted with no effect, you most likely need recovery software, not readers. You know, we have one, BTRFS and all.