Remove the access point from ceiling and please try to connect a new Ethernet cable. If the issue persists please share the picture of the access points connecting to the switch and its still not getting power.
For testing the new Ethernet cable we will have to tear the house apart as the Ethernet cable is running from basement ruckus switch via the three floors. When you mentioned try a new Ethernet cable, I'm not exactly sure if you really meant that, as that's very obvious to try replacing a cable. Aren't there other mechanism to see if the wire is really bad, or is it just the end points on the Ethernet cable which could be looked at for possible issues or the access point itself. As I mentioned it's hard to reach the ceiling and if there are other simpler troubleshooting steps we could try.
What I meant to explain is I wanted you to remove the access point from ceiling leading to the location where the switch is connected and test it with the other ethernet cable.
Note: With these you can confirm if the issue is with the ethernet cable or the access point, please share the picture incase if the access point is not powering up after testing with the other ethernet cable.