I had installed the https://github.com/dangowrt/owrt-ubi-installer and got the device working but after making a change to upstream dns routers the device rebooted. When it came back it was some sort of initial openwrt, no password & factory reset Openwrt. [honest guv, never touched the reset button!]
Oddly the radio entity for the the 5.8Ghz had completely disappeared. Just leaving the 2.4Ghz radio with the openwrt disabled wireless config.
I've tried installing an earlier config back up I had made but it didn't make hold (on reboot no sign of the config), did a hard reset [reset button and power cycle], still the same and that radio is not coming back.
Next steps? restore the Belkin firmware? Or is there some other low level checks that can be done to see if it can be resurrected?