Help with Anchorhead 2018 - Near end of the game

I’m very near the end of the game (fairly sure), but I’m currently stuck because I’m

handcuffed to a rock

I suspect I’ve missed an item somewhere - there was an earlier puzzle that also seemed like it would benefit from this item - but that had an alternate solution, which I used.

The real estate agent’s desk

The only other puzzle that I haven’t solved, in case I have to go solve that one first, is what to do about

the madman

Any hint about where to look would be appreciated.
Thanks in advance.

i got your answer. i needed it to once i reached this part. i got it from a steam discussion here. … 563411317/

you’re going to have to backtrack a bit

Thanks for the link to the properly spoiler tagged site, that’s about the level of tip I was looking for. I’ll search the asylum again.