RN-316 Failed boot after update to 6.7.3 - SOLVED (for me at least)

Hi

Before I updated my firmware I backed up to my other NAS and mirroered that to its mirror and performed a full tape backup (8TB)
Like many others I updated from 6.7.1 to 6.7.3 using the GUI, shut down and the next day had the dreaded

mount_block_root+1f1 error

I tried the recovery tool and several differnet USB flash drives

I turned off

turned on, wait for white circle to go dar, press and hold OK, wait for boot from USB, only for it to sit there for many tens of minutes or it says booting and only to

say

mount_block_root+1f1 error again.

I tried the rufus method

I downloaded latest  rufus-2.15

I copied a version of the USB tool to a directory on my PC.

I formated and created a flash drive with syslinux 6.03

copied over the saved files

inserted flash drive in front slot under door

Booted my RN316

Boot from USB

then after about 2 mins

Booting.....

and then no error, it turns off

Removed flash drive

It booted to 6.7.4

It performed some housekeeping

It booted OK.

I've shutdown and rebooted and it seems to be fine.

.

In future when new firmware comes out, I'm going to wait a week, check the forum and see.

My old RND6000 pro has never given me any trouble, nor my Thecus, Qnap or Synology. I guess the domestic netgears are cheaper for a reason.

 My desktop OS

Windows 10/Kali Linux 2.1/Mint 18.1/