sounds like there needs some adjustment needed on the rods inside the door.
If you have pulled as hard as you can on the inside handle, (Presuming you dont mean the button is stuck down locking the door) then you could try taking the inside pull handle trim off (single screw) and seeing if you could somehow pull the rod a little further over to release the door.
If you get it open then the door card needs to come off and the rods have some adjustment both on the outside and inside handle.
I hope this helps.