This does not sound like a tantrum. Not sustained self injurious behaviour against a wall.
Then there is the not wanting to be held, touched. Nothing making a difference.
Next time (if) that occurs, op you need to put a cushion between him and the wall, let him hit the cushion.
No noise/stimulation or very little...soothing music is best, or something he likes (we use Dantdm talking on YouTube for dd's meltdowns - she knows his voice and he is predictable. She never has liked music/singing)
Space, and time to come out themselves. Do not rush them.
Reassurance that you are there, and that you understand
Readiness to catch them when the fall out starts
No point taking his temp while he is doing this either, he will be warmer because he is burning energy. Always best to wait until he has calmed to get an accurate reading.
Plus, to him it would feel very invasive mid meltdown
I agree though, if this is out of character, and you can see an intimidate trigger then please get him cheeked out. And this may be for other reason than to have on file with the dr that he has begun self injurious behaviour.
*Infographic and further information here