Are there any Registered nurses out there, or maybe you can still help?

I am a 47 year old male enrolled in core classes at a community college on my way to enroll in the R.N program in about less than a year.I have heard that they have a rigorous background check( FBI, mental status from the past and so on.)to enable a person to be in that program. I have no criminal record, but the only thing that might hurt me is that I got out of the military after only a year and a half of being in there. I got a general discharge under undesirable conditions and my DD form 214 said that I could not enter again. I was only 18 1/2 at the time, do you think that will hurt my chances?Should I forget about it and get another major (cause I won't get picked?), or maybe I can go talk to someone at the school.