Had the same issue with the new firmware that several people here have. To reset it unplug the power, hold down the reset button, and keep holding it down while you plug the power back in. The power light should slowly start to flash.
You should be able to assign your local machine a static IP of 192.168.1.5 (or something that is in the 192.168.1.0/24 subnet), and then point your browser to 192.168.1.1. If the router is in rescue mode you should see a web interface for uploading a firmware, rebooting the router, or resetting the NVRAM values. That's about all you can do in this mode. You don't need to use the recovery CD like some people have said since this web interface does the same thing, and I prefer the web interface myself over dealing with an app when it comes to routers.
One thing to note is that after it restores the firmware through the web interface it makes it sound as though the router should be accessible again after a quick reboot. I've done this twice now, and it takes upwards of 10 minutes for the router to complete the restore. Since there is no progress bar it is easy to assume that the restore didn't work and you'll be tempted to try it again. Just be patient though.