Wrt the homework, you could try a form of errorless learning - where you start with a tiny exercise which you know he can do perfectly. Reward him massively for completing it. If he doesn't try, or doesn't complete, no reward, but equally no sanction - just no comment at all about it, be completely neutral. Start with something more 'fun' than work, so even something like colouring in, or stickers.
Each time he tries something give him a huge reward, so he associates the trying with the reward. When this has been mastered (might take days/weeks), you can very gradually move towards work which is more challenging for him. But only on a graduated scale, so eg 4 days out of 5 you give him a very short, easy thing, then one of the days it's something a bit harder.
Every time he does it without blowing up, give him a big reward. If he does get angry, just be neutral, no response at all, just stop the work and do something else instead, with no comment other than "ok let's do xyz now".
This might work at least to reduce his anxiety about actually starting the work, as it does sound like a confidence issue about starting the work, rather than the work itself being too hard, so this approach could help with making it more fun and less stressful, as he hopefully won't realise that the point of the exercise is getting him to sit down and start it, rather than how hard the work itself is.
Wrt the rest of the behaviour at school - what support does he get? Does he have a statement? How do they deal with all this?