Try factory resetting the AP by pushing and holding the reset button for 12 seconds and then connect a laptop directly to the AP and see if you can access it.
If AP is connected to wired network and gets an IP address from the DHCP, you may need to find the IP using DHCP server's lease table or using an IP scanner application. Once you find the IP, access the AP using GUI or CLI, both should be available.
If AP is not getting the IP from DHCP (or in the isolated network), then try to access AP using it's default IP (192.168.1.0/24) by connecting a laptop to the AP directly and assigning same subnet IP to laptop's Ethernet interface.
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