Reflash Asus WL-520GU

Reverting my old router to DD-WRT because current LEDE is too heavy for its old brain.
This is a reminder for me about how to do it.

Power up with the black reset button held in, keep it in until the power led starts flashing. The router is now in TFTP recovery mode.

It has a static IP address of 192.168.1.1, and doesn't do dhcp on the link.

So, plug cable directly into the computer, and manually set up the interface:

sudo ip address add 192.168.1.10/24 scope global dev enp3s0
sudo ip route add 192.168.1.0/24 dev enp3s0 proto kernel scope link src 192.168.1.10
tftp 192.168.1.1
>>> mode binary
>>> put dd-wrt.v24_mini_asus.trx

I also had to reset the NVRAM to reset the login password. Power up, he power light will blink. As soon as the power light turns off, press and hold the reset button. Hold the reset button until the power and wireless buttons glow green.