This afternoon, I followed the onscreen prompt for firmware update from 6.9.0 to 6.9.3 on both units.
First one took the update successfully, and I was able to log back in upon the firmware update completion. Performed the same process on the second unit, and it got bricked on the v6.9.3 firmware update from Netgear.
As others have noted, this appears to be a common problem due to a faulty firmware release.
My findings:
If I create a recovery USB per the support instructions, with the USB in the front port, the unit will boot, discover the USB and show "ReadyNAS USB Recovery".
It appears to do access the USB recovery drive as I can see the LED illuminate several times throughout the recovery process, then powers down as expected/described in the recovery steps.
I remove the USB recovery drive, and power on the unit via the front power button. Once again, by itself, it enters "Boot from USB" mode, and "Boot from USB failed" shows soon therafter on the LCD.
While this unit may be outside of the normal warranty, I don't understand why I would have to replace the unit for applying a software package that was suggested and delivered by the manufacturer. It was fine up until then.
I have used 6 different USB thumbdrives of different brands and capacities as I read that this was recommended by Netgear.
I can't see any problems other than that it's always trying to boot off USB each boot.
One user pulled his box apart and put it back together again and it started working for him, but doing that could easily lead to the unit not booting at all.
I should update my custom tool for booting off USB to be based off the 6.9.3 firmware so it'll be suitable for use for providing you with access to your data.
My tool has been updated. Your data should be accessible over SMB now.
Did you purchase this unit less than 3 years ago and if so, do you still have a copy of the Proof of Purchase?
# dmesg
indicates that there are a number of bad blocks on your internal flash
[ 757.377100] ubi0 warning: ubi_calculate_reserved: number of bad PEBs (8) is above the expected limit (1), not reserving any PEBs for bad PEB handling, will use available PEBs (if any)
So the problem could well be that the internal flash in your unit is failing/has failed.
