Take into account with my description that I'm also autistic, so I might experience things others don't.

Shutdowns are when things get so overloading that you stop being able to process things. Things stop. What stops isn't always the same time to time, but things are stopping, and not capable to do anymore.

Mind goes foggy, can't think. Can't remember. Except its uneven, some things are easy, and others are hard. Which makes it hard to identify what's going on sometimes because some things are easy still.

Speaking skills go downhill. Movement abilities go downhill. Much more clunky. Robotic. Not really fluid or human-seeming.

Sensory processing is messed with too. Information is coming in but it doesn't mean as much. Cars are bad. Avoid cars. Roads are bad avoid roads. Stop at roads. Don't walk into them without making sure cars aren't there. Deeply ingrained information. Other information. May or may not be processed.

Someone's speaking. I can't understand what they're saying. I know there's noise. I might make the connection to try to ask them to type. Reading is easier. I might make the connection to ask to repeat. I might not. I might be locking up too bad.

Walking. I might walk into trees. Or I might freeze and stop and not be capable of moving. But I'll get to that more later.

If I'm interacting with people I'll end up mood-wise one of three ways as I'm heading towards shutdown
a) upset
b) immature
c) just out of it

Speaking. Some I just go non-verbal. Not just "speaking isn't natural" but "no matter how hard I try I cannot cause words to come out of my mouth". When this happens its a few hours to recover my voice.

Freezing. Sometimes I just freeze and go catatonic. I can't move. Again, not a choice. This one its about a half hour to recover if I'm doing it on my own but there are ways to shorten it.