Install With New EdgeOS TFTP Recovery Boot Loader

Has anyone successfully installed OpenWrt on an Edgerouter X that has the new (as of v 2.0.4) Ubiquiti bootloader installed on it? I've hooked up a USB serial adapter to the serial pins, fired up PuTTY at 57600 baud and tried to hold down the "1" key while it powers up, but nothing happens - no bootloader menu comes up in the PuTTY screen from which to flash OpenWrt.

I can flash the Ubiquiti recovery image over eth0 if I put it in TFTP mode (reset for ~30s until solid lights, release, wait for sequential blink through, then put the recovery image to host, but the bootloader only accepts Ubiquiti signed images in this TFTP recovery mode- it rejects the OpenWrt binary.

And a reminder (embarrassing for me - it took me a week and I needed to get help on the Ubiquiti forum!) if you do this: don't forget the Edgerouter does not come up with a DHCP server running on eth0 by default. You need to manually set your workstation to 192.168.1.x in order to reach the router on