Have you tried the built in communications tests between Dual Band modules and other Access Points?
Try a power cycle to see if it is just confused.
Look at the white label on the back. Is it any hardware revision 2.?. They where built on the same 2413 base PLM board. That has a known issue the its power supply and failing anytime after the two year warranty. I had two of my 2443 V2.5 fail. I rebuilt mine with new low ESR capacitors.
Another clue maybe the LED on the side is dimmer than usual.
Range Extender is the present module as pointed out. Some have used a plug in module like the Dual Band ON/Off or Dual Band Lamp module. As the extra features maybe used at a later time. The Range Extender is a Dual Band Lamp module with the dimming parts not installed.
I did the 4 tap on the access point. I got other devices to respond. An the opposite, I did the 4tap on a plug-in dimmer and got the AP to respond. However, depending on where I plugged it in I got mixed results (all in close proximity. The device is V1.0.
Doing all this testing I noticed that one of my in-line dimmers has an issue. When turned on through X10 button the lights attached to it go on/off forever until I click X10 off twice. The light attached is low voltage kitchen lights. So, in theory it could also be the transformer. I did cycle the circuit breaker. Same behavior afterwards.
Is the transformer rated to be on a dimmer? Many times a dimmer driving a transformer does not work. Some times damaging the dimmer, the transformer or both. Can you disconnect the transformer while powering the InlineLinc and see if it still pulses?
Yes, the transformer is dimmer rated. I got 3, installed many years ago. However, I suspect this is all related to my issue with a 2475D. I recalled that I had the same type of dimmer (2475D) somewhere else installed. At his 3rd location I can install a dimmer with faceplate. As a result I confirmed that the 2475 was defect.