Okay, I admit it, it took me more than an hour to understand the code. I've also heard of many others who did, so I'll be making this guide for new players xd
 

Simple enough:

The note located next to the elevator isn't very helpful, so here's an updated version:
 
 

 
 
Here's how it looks on-screen:
 
 

 
 
Here's an example:
 
 

 
 
I hope you found this helpful and have a great time.

 
 

 
 
Hope you enjoy the Guide about Inside the Backrooms – Elevator Code, if you think we should add extra information or forget something, please let us know via comment below, and we will do our best to fix or update as soon as possible!