Sadly there are a lot of people replying who clearly have no understanding of ND teens or the struggles they face. At 18 an ND teenager can be 3 years behind their peers in emotional maturity. What do people suggest they do? Wait 3 years before they go to uni? No, what they need is proper support and for people not to say 'you're an adult now, you're on your own ,work it out'.
Struggling to ask for help is as typical as it gets for an ND kid, especially when they don't trust the person they're expected to ask for help to respond positively - ds is the same. But he's now doing a degree apprenticeship where he is so well supported that suddenly he has no problem discussing any issues he has with his fantastic boss. He absolutely loves it, but it's software engineering rather than engineering. Your DS needs tutors he likes and can trust if he is going to be able to ask for help IMO. Sadly his tutor sounds like an arsehole.
The library might be completely overwhelming to him OP, has he been shown round at all? It sounds like he really could do with someone to take him around and show him how it all works on a 1;1 basis to help him really take it all in - I wonder if thee are any 2nd or 3rd year student volunteers that help ND students with this sort of thing?
He also really needs help with planning his study and his assignments and revision. I would recommend you help him with that as much as you can if he does go back OP, helping him structure his days and keep on top of what he needs to do. ND kids need someone to teach them how to do all this and it's probably something you could help him with a lot. DS did an EPQ and had to do an NEA during his A-levels and I taught him as much as I could during those about researching and writing in a way suitable for uni.
What uni is he at OP, in my experience of (just) visiting unis many care about their research much more than they care about teaching their students. I found generally the ex-poly's were much more student centred than the RG's. The difference between Southampton/Exeter and Surrey for example (for comp sci) was stark in this respect.
I think you definitely need to get a lot more involved OP if he will let you - don't listen to people who say 'oh he's an adult, you need to step back and let him work it out for himself' - those people are clueless about what works for ND teens.
What I do think he now needs to consider is if engineering is for him. If he still really wants to continue then he need to decide if he wants to continue here or go somewhere else. He might be better off living away at a uni that is much more supportive - but with you keeping up with everything he's doing, his deadlines etc and being much more involved (if he'll let you). Or he could change to another course either at this uni or another one. Does he still see himself working as an engineer at the end of it? Do you think it's a role that would work for him?
I definitely don't think he should just decide uni isn't for him just on this one bad year. I also don't think engineering apprenticeship are necessarily the answer - they are generally hugely, hugely competitive and he may not stand much chance straight off the back of a failed year at uni.
I do think once he gets settled he also needs to start thinking more about what is going to happen at the end of his degree. To get a job he is going to need to stand out from the thousands of other students doing engineering that finish at the same time as him. That really means getting involved with societies and eventually taking leadership roles, having a part time job, relevant volunteering perhaps something through university - maybe even helping other ND students - that sort of thing. I talked a lot about this with DS when he was planning on going to uni because a degree is just not enough to get a job now.
Good luck OP! I really hope he gets loads of support and finds a path that works for him.