I just played it again just for fun and I stumbled upon the **se**nt and saw just a weird looking wall so I thought it was a glitch or some sorts. Didn't know I can go through it. First reaction going in was like OMG.
I have recently played the game again and to my surprise I couldn't get it again.
My conclusion is that I was very very lucky to find it the first time. Also yes its in the basement all the way at the end. If you're lucky enough then the far end wall would not be a wall and will be black
