Goosey:
UPDATE - still cant see the AP's IP address on my router...
IME if its blinking white, its trying to provision so it will show on any controller on the same network with its actual IP, if its not got one then 192.168.x.20 (cant recall x) - if you're seeing nothing then I would be guessing a failed ethernet interface. No link light on the AP, and if you dont have lights on your switch to show speed it might be seeing a load and lighting up because its doing 10 megabit since it sees a load but no negotiation of higher speeds.
Get another AP, and this one may still show up as adoptable wirelessly if the radio side of it is still all good, in which case you could keep it and use it as a repeater.