My daily rant! This guest just doesn't follow instructions

I’m sorry for posting this but this is my rant of today.
Today’s guest has just sent me an irate message complaining about everything there is to complain about my check-in process and I’m worried he’s going to leave a poor review afterwards.
We offer a self check-in service and I have compiled a pdf explaining everything in detail. This guest has listed several items he wasn’t happy but they were actually all explained in detail in the pdf…

I even messaged him 3 days ago with further instructions and followed up with another message yesterday, which he replied to and he clearly missed the small detail in those messages as well, but blamed me again for something else.

Just really annoyed because everyone else have been very happy with the check-in process and some have even complemented the concise instructions provided but this guest will probably leave poor feedback due to his own inadequacy.

Communicate all through the Air system… all the details of his “problems” (eye roll) and make sure to reiterate that this information was provided on xx page of the guest info document. Just be patient and keep repeating … this is on page xx, this is on Page yy. You will probably get a bad review from this loser, but if you handle it correctly, there might be a chance Air can remove it.

Is it possible to offer a part refund halfway through a stay. I don’t want a bad review over something so trivial.

A refund won’t do a damn thing to stave off a bad review. I learned this over the New Years holiday with my second worst guest ever.