To perform this step, hold down a reset (or restore) button for a few seconds, or choose the option to restore factory defaults from the Administration menu in the router's Web graphic interface. Our Asus RT-N16 supported both methods, so we chose the hard reset option. We held down the reset button on the back of the device for a few seconds, and waited for the router's power light to start blinking; then we released the button, and let the router reboot.
2. Upload the initial firmware: After the router rebooted, we opened a browser window and accessed the router's Web graphic interface. Some routers (like our RT-N16) automatically launch a configuration wizard the first time you open a browser window after performing a reset to factory defaults. Other routers require you to type the appropriate IP address into a browser--typically 192.168.1.1 or 192.168.0.1--to access the Web interface. Do whatever your router requires for this step (the information should be available in your router's manual or on the manufacturer's website).
Our RT-N16 automatically launched a configuration wizard, so we simply opened a browser window, and completed a few prerequisites (such as setting a password and a Wi-Fi passphrase) to expose the Web graphic interface's home-screen option. Then, at that home screen, we clicked first the Administration link in the main menu and then the Firmware Upgrade tab at the top of the resulting screen. On the Firmware Upgrade screen, we clicked the Browse button, selected the initial DD-WRT mini firmware file for the RT-N16, and then clicked the Upload button to commence the initial firmware upgrade.
After installing the initial DD-WRT mini build, you must let the router reboot on its own and then settle into an idle/usable state. Be patient. You'll know that the router is idle when all of its lights have stopped flashing and your PC has obtained an IP address; the process usually takes a few minutes. When the router is ready, power it off (unplug the power cable if there is no on/off switch), wait a few moments, turn it back on, and then immediately hold down its reset button for a few moments to clear its NVRAM and restore its factory defaults once again.
3. Upgrade your version of the firmware: After the initial flash of the DD-WRT mini build and factory reset, you must once again access your router's Web graphic interface. After DD-WRT is flashed onto the device, regardless of how the router behaved before, you'll have to access its Web interface by typing 192.168.1.1 into your browser's address field. The first time you do so after flashing the mini build of DD-WRT, you'll be prompted to set a username and password. You can configure the credentials any way you'd like, but set a username and password that you'll remember, because you'll need them in order to change the router's configuration later, and you won't be able to recover them if you forget what they are. In that case you'll have to reset the router to its factory defaults again, and configure all of its options from scratch.