Im trying to trap him (and take the gold of course) but even after following a video tutorial I cant win. I tell him Im not even interested in the vault so he agrees to come down. With stealth boy and hidden behind generators and walls and stuff, he always somehow sees me even when I cant see him at all.

I even tried standing by the door just like he wanted and he still stops in that one doorway and activates the alarm systems.

What am I doing wrong?

EDIT: Im finding my problem is it never gives me Option B: Sneak past him. It only says Defeat him, no matter how many times I reload, ive even reloaded to before I entered the vault itself and tried but still nothing. Can someone please help me? This DLC has been the buggiest thing I have ever played, which is a huge dissapointment cause I think Fallout games and Elder Scroll games are the greatest games ever made