In my case, I was referring more to a non-terminal psychology-oriented masters program, which can help both with the GPA and limited research experience issues.
Although while a non-traditional approach, if your MBA GPA is solid, that could alleviate some POI's concerns about your ability to handle academic coursework. If you could add a year or so of research experience (even if "only" part-time, such as through volunteering in a lab), that might get you into more places than you're thinking.