The TVS diode, marked D6 on the PCB, is located between the antenna and a large IC on the RJ45 port side of the board.

It is a 24V uni-directional TVS diode with J leads (SMBJ24A) made by Littlefuse. Note the location of the white bar on the diode, as it indicates its orientation.

Use a multimeter or ohmmeter to test whether the diode has shorted. A shorted diode will read less than 1 Ohm in both directions. A working diode will have significantly higher resistance in one direction than the other.

If the diode is not shorted, then there may be another issue, and proceeding further may not help resolve the problem with your access point.