I know this one well. My son has autism with sensory processing disorder and anxiety, and after about a 1.5 year process, he is just fine getting a haircut. He was the crying meltdown, afraid of the noise, said it felt weird and scary kid so we did a few desensitization sessions. I got some of those clippers advertising sensory friendly or whatever term they used and basically pretended I was doing a hair cut session. I got him ready in front of the mirror just like at the barber and then we talked about the process, I let him touch the clippers and feel them in his hand buzzing, put them close to his ear to hear, then closer the next time, and time again then one day I was able to cut it while he watched in the mirror to see I wasn’t gonna hurt him and haircuts don’t hurt.

The trick I used to get him to the barber, having another favorite adult take him in the first time. I had my dad take him and my brother together. Once he saw my brother in the chair he was ready to be a big boy and did it like a pro. He didn’t have his normal reinforcements of mom or dad to support him and he realized he was okay and could do it. Now it’s a normal thing to go get a haircut and he wants it now because that means he won’t need a deep combing with his type 4 curls. Cutting became better than combing.

We walk him through it every time. We let him hold the clippers. We watch a show about getting a haircut beforehand. Distractions work okay. He’s usually less whiny after a few minutes. If that doesn’t work you could probably get him used to trims with scissors.

Can you trim it with scissors while he sleeps. Or get a hairstyle (braids or ponytail) that allows it to be functional while it's long

I should say we would do this for home hair cuts and qhen going to a salon. They didn't mind the phone because it kept him still and no meltdown. He does perfect at the hair salon now.

We had this issue when my son was younger and we had to cut his hair ourselves with special clippers that were quiet. He has Autism and it would be a full vlown meltdown, crying, etc. Finally what we found that helped was letting him have our phone and putting on a show. At that time it was Peppa Pig and that helped distract him. After so many times of doing that he finally was able to not use the phone and has been great with hair cuts since.