ZyXEL nas326 installation problem (1 reply)

I'm trying this with the ZyXEL nas326 (method B - usb installation without serial) and encountering similar errors as were mentioned here before by @nastynas, notably

* the firmware is reset every time it reboots - ssh access is disabled until initial account setup + configuration
* occasionally locks up on boot (unresponsive, all leds deactivated)

The dmesg boot is here - https://pastebin.com/XqBD2dnP

The steps I followed were

1. ssh access to nas, run fw_printenv (output available https://pastebin.com/8ErKPCtm)
2. run fw_setenv commands, printenv output again ( https://pastebin.com/neMfh8TT )
3. setup usb with Debian-4.12.4-mvebu-tld-1-rootfs-bodhi.tar.bz2 - single partition ext3 with label 'rootfs'
4. sync, unmount usb and insert into nas device
5. sync nas via ssh, and reboot via /sbin/reboot

after step 5 the nas will boot backup into the stock firmware and all the settings will be lost (admin user resets to factory version, ssh disabled + config lost). I've also tried with a cold boot and many (many) reformats of the usb. Where can I go from here?

Thanks for your help