A lot of Unifi access points run with 24 supply voltage. Some people seem to brick them with supplying 48V POE. Fortunately they have a over voltage diode which can be replaced easily.

= UAP AC Lite =
 * remove and/or replace Diode D6
 * https://de.ifixit.com/Anleitung/Ubiquiti+UniFi+AP+AC+Lite+TVS+Diode+Replacement/73360

= UAP AC LR =
 * remove/replace Diode D1
 * http://www.setfirelabs.com/wifi/ubiquiti-unifi-repair

= Spare Part for D1, D6 =
 * LittleFuse TVS Diode Uni-Directional SMBJ24A-E3/52 38.9V, 600W, DO-214AA 2-Pin
 * http://www.littelfuse.com/~/media/electronics/product_catalogs/littelfuse_tvs_diode_catalog.pdf.pdf