Root Boot Loop - Recovery & Download mode work but no OS


Often Off Piste
My note 2 was set up like this:
resurrection remix rom 5.5.9 lollipop
rooted supersu 2.49
nandroid backups on installed sdcard
last stock rom was 4.1.2 (early bootloader)

It got knocked on the floor and the battery fell out. Upon reboot it had uninstalled every app including all gapps - just rom apps present. I reinstalled the OS and gapps from scratch and it worked fine until..

A week later it rebooted without reason into a boot loop - without the loop, stuck on Galaxy Note2 logo.

It will boot into download mode
It will boot into TWRP - but twrp cannot mount any partitions (cannot mount sdcard) and says "no OS installed"

I have tried Heimdall to install a stock rom from my linux PC. It recognises the device but will not install due to no USB permissions (I suspect USB debugging is/was not enabled)

I think the device may have a hardware fault (and is beyond recovery) but if anyone has any ideas I'm listening!