with beta5 the link to luci is misspelled/relative. Is pointing to 192.168.8.1/192.168.8.1/cgi-bin/luci - and without any Button.
the same error was in this FW for a lot of routers. I have N300/ AR750S/AR300M. In the FW from 28 March link to LUCI works better but still without button.
The firmware has reached Beta 5 already?
Beta 6 actually