Sean is Handcuffed to a pipe in the gas station during Life is Strange 2 Episode 1. To get him out of there you have to break the pipe anchor and get the keys from the other side of the room and give Daniel the keys through the vent. Start by turning on the monitor in the room to get more light. Next up, look around the room until you can talk to Daniel through the vent.
Ask him if he can enter through the window. He then turns on the neon sign outside and you are able to see the keys next to the door. Go right and check out the pipe anchor that you need to break in order to get to the keys. Ask Daniel through the vent for some tool and break the anchor with it. Sean can now go alongside the pipe to the keys and escape the gas station with Daniel.