We had the same issue with one of our APs initially. We set it back to just DHCP in the dashboard after a reset. This way it showed up and then we reconfigured it with a static and VLAN info. Once it shows up with a DHCP address make sure you note all the info it has in the dashboard. Maybe you misconfigured the VLAN, gateway or something else.
T Roberts
A+, Network+, MCP, Dell and CMNO