Just tried the TFTP process on another computer (different OS, different network chipset). Now all I'm getting is a power light - nothing at all on the LAN ports.
Update - the power light sat orange for a bit and just went to solid white.
Update 2 - I can finally get to the web interface on it! Might be getting somewhere...
Unfortunately, my router appears to have been bricked by this. I went to login to the router and got the "DumaOS not loaded yet" message. I rebooted the router and it is now stuck with just the ethernet port LEDs on and the power LED. The wireless is not coming up at all. I plugged a computer in to a hardwired port and it is not getting any IP address. I tried doing a factory reset with the button on the back - no change. When I hold down the reset button for a few seconds, the power LED goes off but the ethernet ports stay lit.
Any ideas on how to resolve this?