After install you need to set the IP address:
uci set network.lan.proto="static"
uci set network.lan.ipaddr="192.168.1.70"
uci set network.lan.netmask="255.255.255.0"
uci set network.lan.gateway="192.168.1.1"
uci set network.lan.dns="1.1.1.1"
uci commit network
/etc/init.d/network restart
after you need to install LUCI:
opkg update
opkg install luci
Also I think it is necessary to redo these commands that after installing the firmware from the "before" installation of LUCI (go overwrite the firmware...)