Try to factory reset AP -- you need to connect pins 4-3 (the two
on the right side, top and bottom) on DC power connector for 10 seconds.There is a special shunt delivered in AP box, but paperclip will do. When Ap reboots after reset, it must answer to default address 192.168.0.1. If still not successful, try again. In the worst case connect PC with Wireshark and check if there is at all any activity on Ethernet port, than try second port. If both ports fail, you may have hardware issue, which is pity if warranty is over. But in my experience ZF7762 is almost undestroyable device. I have experience recovering one AP which was installed on pole without cable gland. PoE connection failed after 1 year in February, when cable socket was full of snow. After such abuse simple cleaning of PoE port socket restored AP to life, and it still works flawless (>2 years).
If your PoE switch is on a network with DHCP, the 7762 is probably picking up an IP address. Look for it's MAC address in your DHCP lease table if you have a local router. If no ZD/SZ picked it up, you should get the factory default AP login screen from the IP address it's using after you find it.