ar71xx

Flashing

Connect an ethernet cable from your workstation's ethernet port to one of the LAN (not WAN) ports on the router. The router will be on 192.168.1.1.
Set static ip in 192.168.1.5/24 on your workstation's ethernet port.
Create symlink to .img due to tftp being picky about long filenames:

cd openwrt
ln -s <locationof>.img factory.img

Start the AP up while holding down the reset button. Once the power lede is flashing green you can let go of the reset button.

The AP is now ready to accept a new .img, continue with either method below:

Use the flash script:

cd openwrt
./flash

This will also update the .csv with the mac address

Manual interaction with tftp client:

ln -s <locationof.img> factory.img
tftp 192.168.1.1
> bin
> put factory.img
> quit

Assuming Openwrt is already installed:

scp <sysupgrade.bin> root@<AP IP>:/tmp/
ssh root@<AP IP>
cd /tmp
sysupgrade -v <sysupgrade.bin> # Wait for the AP to load and reboot

Once it comes back online ssh back in an confirm the version

ssh root@<AP IP>
cat /etc/os-release