Due to a foul-up during the initial firmware flash, I've bricked the node - it's a brand new Bullet M2HP XW revision. I removed power too quickly after the flash before the firmware was successfully installed.
Attempting to reflash, the device successfully goes into TFTP mode, but the IP address is unknown - it doesn't answer to 192.168.1.20.
In previous versions/devices, I've been able to attach a serial interface to the unit, interrupt the boot loader and rewrite the stock IP address (192.168.1.20).