1:You cannot log to the APP if you are not connected to the Access Point SSID/Wi-Fi signal.
Note: even if you have enabled remote access will no work either, if it is not online.
2:If you cannot even see the SSID, I can guess the APs are not even powering up.
3:So the first, will be checking if the Switch, which is the one that provides data en power to the Access Points is fine, it may be a ICX7150 Switch (same brand as the Access Points), so check the next in the Switch:
A:It's turn on?
B:Is the system LED light, amber, or green.
C:Are the Ethernet ports light up?
D:are other devices that required power from the switch working fine, such doorbells, cameras, so on?
E:If you connect a computer to the Switch via wired, is getting connectivity to the internet or not?
Technical Support Engineer | L2 TAC Wired