RN104 Retry Startup

I have been using this NAS for over a year, but a few weeks ago it failed to boot, and I get retry startup.

I have instaled Raidar on my mac and can see the device.

When I log on using the standard password I can run diagnostics, and I see the following.

Any help would be greatly appreciated.

Cheers 

Keith

Successfully completed diagnostics
System

Logs
2016-05-30 19:40:10: md/raid:md127: failed to run raid set.
2016-05-07 23:00:34: md/raid:md127: failed to run raid set.
2016-05-06 13:48:27: md/raid:md127: failed to run raid set.
2016-05-06 13:45:18: md/raid:md127: failed to run raid set.
2016-05-06 13:42:33: md/raid:md127: failed to run raid set.
2016-05-06 13:13:03: md/raid:md127: failed to run raid set.
2016-05-05 23:22:37: md/raid:md127: failed to run raid set.
2016-05-05 23:13:40: md/raid:md1: Disk failure on sdb2, disabling device.
2016-05-05 23:13:27: BTRFS: error (device md127) in btrfs_commit_transaction:2084: errno=-5 IO failure (Error while writing out transaction)
2016-05-05 23:13:09: md/raid:md127: Disk failure on sdb3, disabling device.
2016-05-05 23:12:49: md/raid:md1: Disk failure on sdc2, disabling device.
2016-05-05 23:12:01: md/raid1:md0: Disk failure on sdc1, disabling device.
2016-05-05 23:10:28: md/raid:md1: Disk failure on sdd2, disabling device.
2016-05-05 23:10:22: md/raid:md127: Disk failure on sdd3, disabling device.