Does remote work? If you own a digital camera, use it in "video mode" to film the output of your remote control....point APEXRemote with new batteries at the video and press any buttons on remote....you should see a "lighted flash" pattern corresponding to the output or button pressed. Most new digital cameras are "IR sensitive" and detect any IR light pulsed out of most remote controls' IR LED. All use an "IR LED" which outputs infrared rather than visible light.
I use the camera on my tablet to "see" if a remote still works.
Another time, a satellite receiver I had with no replacement remote available was made to work when I re-powered the remote itself (I thought it was bad....) from an alternate source. BATTERIES alone weren't strong enough to run remote.....I used a 5v USB power adapter to run with a thin cable into battery compartment. Worked great!!! Remote needed more power, I guess.....
Suspect the remote if the power supply on APEX box is still working 100%. Otherwise, that is next thing to suspect.