I had this problem when I had a neo 2.2. Couldn't figure out why the damn thing wouldn't work. I tried it the EA way, and it booted happily.
Hope this helps.
If for any reason you have never booted the EA way:
Power on ps2 with your ar2 or whatever (still holding in the reset button all the time). Go to the start >> start game without codes, and then (and of course you have to do this very fast and very carefully!!), let go of the reset button, the tray ejects, and you have (I think, if I remember correctly) 5 seconds to swap the boot disc for the disc you wish to play, before the tray brutally retracts. Once the tray retracts, push the x- button.
You are probably well aware of this method 3sc0b4r, but this is to help anyone else that may be having problems like this.
If anyone has a better description of the above act, please feel free to correct mine.