My condolences on your son's situation. And while it is very stressful to you to be in a place where you don't know what is happening next, I'm pretty sure your son is in a place where he isn't comfortable either. And this is a learning opportunity for him.
One thing that will serve him well in the military is to learn how to handle making a mistake. There are a few critical things he must do at this point.
1) Accept 100% of the responsibility for the situation he is in. While he may have not have been well prepared for his first semester, he should be counseled not to blame anyone but himself for this (very easy for someone who has been spoonfed how to succeed up to this point).
2) Take the initiative to analyze what behaviors of his led him be in this situation. I suggest that he learns how to make a list because there are probably several. I will suggest several that you may see:
a) Taking classes he is not academically prepared for - Just because a kid takes 4 years of HS Spanish, it doesn't mean he is ready for Spanish V. Many schools offer placement tests for all sorts of subjects. They aren't there to punish students, but to accurately assess where a student should start their studies. This leads me to the second item which is...
b) Not taking advantage of support services offered by his school. Placement testing and academic advisors are there to make sure a student has the information and takes advantage of the tools available to choose appropriate classes and get tutoring as necessary. Advisors don't just exist to sign off on your 104R.
c) Failing to act upon the resources provided to manage one's affairs at school. You can get bombarded with information as they enter first semester. They get a list of where to get help, they get syllabi, they may get a ROTC office where they can duck in during the day to have a quiet place to study between classes.
d) Underestimating the task before them. Just because they got a syllabus detailing the tests to be taken, papers to be written, etc. doesn't mean they put all the requirements to on a timeline and execute. They had tests and papers in HS. They stayed up late and put out a product that was graded and they thought they knew what was acceptable. This isn't Kansas Toto (No offense to that school intended). Failure to understand that winging it on a major project doesn't work like it did in HS is common.
e) Overestimating their level of skill. They may have been in the top 10% of their peers in HS. That other 90% didn't follow them to college. It is a lot tougher competition. Need to get game on.
f) Failure to prioritize. Lots of things to do at college. Some critical, some imporant, some nice to do, some just plain waste of time. Understanding which items are which (once they have correctly estimated the task in item d) is critical. Academics, ROTC events, dorm events, school-wide events. Knowing how much of which you can do to keep one both happy and successful at school is a critical skill. All 24 hours of the day are used - what is he getting from each of them?
g) Failure to prepare. I'm sure that his cadre has told him that failing to prepare is preparing to fail. It applies not only to ROTC activities, but to his studies as well. College professors do not "teach" subjects like HS teachers do. You are expected to have read the material and have some understanding of it before the lecture - something that isn't done in most HS classes. Lectures are there for the student to confirm that s/he has adequate understanding of the material s/he has previously read. It is to review and integrate the concepts in the readings. In case s/he is still lost, office hours are a backup plan to cover something that didn't quite click in lecture.
h) Lack of discipline to carry out the above. Let's face it, students are still kids and when a party comes up the night before a test which was planned as study time, bad decisions are made.
i) Failure to learn from mistakes. Ignoring the fact that last night's party directly led sleeping through the test which the instructor didn't offer a makeup is a common way to deal with the pain of failure. Mom and Dad didn't ground me. Nobody said anything to me. I can just put it behind me - until I do it again and again.
3) Be willing to openly discuss his failings (above) with those who control his destiny (you to start with as he cannot afford to fund college on his own). He should have list above and be able to cite chapter and verse how he got where he is and more importantly how he employ the resources at his disposal (see item 2b) to help him to stay on track going forward.
4) Proactively contact his cadre (before they contact him), present the above and make an appointment to review his plan as soon as he arrives on campus.
5) Once he has dug himself out of his hole, volunteer to help others behind him keep from becoming him - obviously he failed to grab the hands extended to him so far, doing a better job of keeping those behind him from getting in as deep shows not only a lesson learned, but more importantly the leadership skills to understand that the whole unit's success is important.
As to my advice to you - look this over, have an adult beverage (if that is your thing), and prepare to be firm in keeping him moving forward (no pity parties allowed). Time to watch him grow up. He will get there. You will need to be strong to help him.