I will see if I can help you out.
Now you said your fan will come on if you give it direct power, so lets find where we are not getting power.
First of all, here is the wiring diagram for your radiator fan circuit:
Lets start checking some powers and grounds.
You have replaced your fan relay, so you know where that is, and that is where we need to start.
With your engine running and A/C on, check for power at pin 4 (GY) and pin 2 (DB/PK). You should have continuity with ground at pin 1 (BK).
If you are missing your ground, you need to trace that wire back to where it is not getting grounded.
If you are missing power at pin 4, check fuse 10 and the wire between your fuse block and relay.
If you are missing power at pin 2, then you need to make sure you are getting power out of your PCM at C2 pin 17. If not, you have a bad high side driver in your PCM and your PCM will need to be replaced.
If you have all powers and grounds you have a bad cooling fan relay.
I know you said you replaced it, but they go bad all the time on these and I have seen out-of-box failures with these relays.
I hope this helps! Let me know if you have any more questions!