I tried resetting it to no avail. When it turned back on it was switching between having all LAN and WAN lights on (no power/wifi) and having the Power/WiFi lights on (no LAN/WAN), every second or so.

So I reset it again and put it into Recovery mode. I manually set the IP on my computer and used a TFTP client to re-upload my firmware image and reflash the device. To my happy surprise, it was working again. Problem solved.

Or not. I logged into the web interface to change my settings, which went great. I enabled Wireless, chose to Apply settings, and my router almost immediately reset and went back to the flashing lights again, just like before.

I tried this several times with the same result every time. Trying to avoid going insane, I ended up leaving for work and doing some investigation. It turns out I am experiencing the exact same symptoms as a lot of other people whose Asus power supplies have gone bad.

The problem is that a round-topped capacitor in the power supply is prone to electrolytic leakage. It essentially "blows its top" and its contents leak out into the unit. When there is not enough left in the capacitor, the PSU is not able to provide stable power.

The reason the problem only occurred after I enabled WiFi is that the router requires about 0.75 amps to boot up, but 1.1 amps is used when WiFi is powered on. It seems my PSU has enough juice to boot up, but as soon as it tries to enable the WiFi, there is simply not enough power and it gets stuck.

I am very hopeful (and 99% sure at this point) that it is the same issue I have as well. I'm going to stop by Radio Shack on the way home and get a replacement capacitor (hopefully 1200uF / 10v or close). I will report back my results afterward. If all goes well, I'll be making that post from my home computer through my working router!