After a reported successful flash to version 7.2.1 of AirPort Extreme firmware, my AirPort Extreme base station locked at start-up with the status/activity LED solid yellow. It would not respond to AirPort Utility either over the air or via local Ethernet connection, even after several power cycles that allowed up to thirty minutes between attempts.This is dire. AirPort Extreme isn’t just my Wi-Fi router. It’s the NAT/DHCP router for wired client nodes on my LAN. When it’s down, my lab’s clients and one of each of my server’s two GigE ports goes dark, along with the personal Macs and (ugh) PCs in my house.To guard against such catastrophes, I keep a second wireless router (of inferior brand, speed, quality and style) configured to match AirPort Extreme’s settings. I moved two RJ-45s, powered up the standby router, pulled the plug on AirPort Extreme, and my NATed LAN segment quickly returned to service. It’s a process that even a manager could manage. I came back to AirPort Extreme the next day. It booted without incident and it’s now back in full service. I still don’t know what happened. Maybe there’s a supercap inside AirPort Extreme that keeps volatile settings alive while the router is powered down so that it boots faster, and it took a day without power to drain that cap. I didn’t have the presence of mind to see if it took any longer to boot after it recovered.The lesson here is that if you think your AirPort Extreme is toast, unplug it for a day before you read its last rites. The other lesson? If you run a critical WLAN, keep a spare Wi-Fi router configured to plug and go. Software Development