Hello Artman,
Since you said that one of the APs is working, I would recommend you unplug this one and use the same cable/POE setup to test the non-working one. The AP should fully boot up and you should see both (green and amber) lights once done. If using known working POE/Cable and you still see no lights, are unable to reach the AP via console or SSH and it does not look like it's even powered up, then you might want to consider RMAing it.
Thank you,
Chris
Christoph S.