@knacky
In the now closed thread Flashing OpenWrt to Ubiquiti UniFi AP (stock flash ver >= 4.0.15) - #7 by knacky it sounds like you found a way? Can you be more specific please?
Does it boil down to:
- Use
fwupdate.real
to downgrade the bootloader - Write an OpenWrt image without reboot using
mtd write
?