Plugging the AP into the router with an ethernet cable should "just work." By moving a known good device to each port on the router, you've already verified that they're all good, so the AP should work when connected and powered up. Does anything beyond the power LED come on on the AP when connected to the router?
Try using a different cable to connect the AP to the router. It's not likely, but its always possible that you're using a bad cable.
Yes I have tried different cables and the same result. And yes the only light on is the power light. Nothing happens when I press the reset button on it either. I read somewhere that maybe the power supply is bad. So that would cause it not to completely boot. But I have no other power supply to test to see if its that. Its a 5v 2A power supply.