HELP with TFTP recovery on NV+ v1

My NV+ has been playing up.  I have nothing on the discs,so no worries there.

I had power supply issues, which I resolved - dry joints in the SATA backplane!  Having resolved PSU these issues, I'm gutted to find that all the up & down has messed it up. 

It has left the internal NAND storage in the unit corrupted. 

The NAS LCD status screen remains blank throughout all this.  All i get are error codes via the drive lights.

When I turn on I get LEDs 1, 2 & 4, which points to NAND corruption.  Then regardless of what reset steps I follow, I end up at LEDs 2 and 4, which I think indicates an attempted TFTP boot.

I cannot get the unit to do a USB recovery.

I cannot find any instructions on how to execute a TFTP boot.  I also don't know what files need to be presented, or where to get them.  The USB images and the 'firmware' update files clearly aren't the right ones.

I've installed a simple TFTP server on my laptop, and directly connected my laptop to the Readynas, setting 192.168.125.1 as my laptop IP address.  I see no 'activity' in the TFTPD64 window.

This is really low-level borked, and I need some pro help to reload the firmware.

Can anyone help me with TFTP files and instructions for NV+ v1?  thanks