DMay's apcupsd only support serial port ups, the built-in NUT did work with USB APC UPS. It will detect the UPS and there will be some entries in the log to show it. To test it throughly, you can put your SME to the wall power instead of the UPS, plug the UPS usb in the server, disconnect the UPS from wall power, and run out of the battery of the UPS by using a 100watt lightbulb or something like that. When the power on the UPS nearly run out, it will sent a signal to the SME to shut it down.