How do I upgrade my discharge status and change my character of service (RE code) in order to re-enlist?

I was discharged from the Marine corps in June of last year and given an re code 4 and fraudulent enlistment. During SOI I was sent to medical and diagnosed with a personality disorder and then processed out. After returning to civilian life I saw a counselor once and she said ij had no personality disorder or any mental health issues, told me to stop taking the medicine and that I only needed to co time to see her if I felt I needed to. I didn't and haven't seen her since. My question is how do I upgrade my status and change my character of service and re code in order to enlist and how likley is that to happen, with my o ly supporting proof coming from a civilian doctor?