* The wifi access point is no longer visible to laptops and other access devices.

Double check if the power supply still works. Use a multitester to check for absence/presence of power or voltage drop. If your site is using a Mikrotik router (Metal 2SHPn Wi-Fi hotspot Access Point), note that its power adapter has 24V 0.8A rating.
It connects to the access point via a PoE injector.