The inventory system was crap. Lot's of items you don't need and you can drop ones that do.
Because the walk through no longer works I wrote a brief one.
Grab the note in side room(you can write down the digits and drop it)
Read the paper and go to 4th floor
Get the light out of a side room
Use the light and enter the dark room
Drop through the pit to the second
Take the Stairs all the way up and grab the gas can
Go to the 1st floor and turn on the generator with the gas
Go in the security room next to the elevator and grab the key
Go to the 2nd floor and use the key on the body and take the note
Go to the elevators and enter the code.
Use the TNT and step back
A couple more notes. Reloading the handgun uses the clip and sets it the bullets to 15 so only reload when low on ammo. The knife and Axe are both decent weapons. You don't need the bug spray, mop and fire extinguisher. The shotgun can't be reloaded.