I had this same problem... car wouldn't go into fob learn mode (no message on DIC after 5 key turns). Here's what works for me:
1) Put metal key in key cylinder back by license plate. Dont turn it yet, just leave it in there for now.
2) Put old, already-programmed-and-working fob in center console cupholder
3) Turn car 'on' using start button (you dont have to start it -- doesnt matter), then press start button again to turn car OFF.
4) Immediately run (yes, RUN) to the back of the car and turn the key five times. If you physically cant get back there very fast, have a helper ready to turn the key five times when you turn car off. This should trigger the "FOB" message on DIC.
5) Carry out the rest of the fob learning procedure as normal.
This is the ONLY way my car will go into "fob learn mode". If I wait even 5-7 seconds between steps 3 and 4, my car will never go into fob learn mode, no matter how hard or fast I turn the key.
Keep us posted on your results...