Looking for help with stubborn bend on binding-side corner

I am trying to fix a beat up Something is Killing the Children #1, and I’ve had a lot of luck aside from the top left corner. The entire corner was bent forward, creasing all pages, particularly the covers and the immediate pages in the front and back.

What Ive tried: I’ve hit it with a tac iron and it’s a lot better, but I’m not getting much better. I may have made a mistake by pressing the book already, hoping the paper was loosened up from the iron heat, but alas, it didn’t fix it as much as I’d hoped.

I don’t know where to go from here and before I start experimenting with a potentially expensive book - as I’m very new to this - I wanted to get some feedback. I was wondering if it was time to use humidity and if so, advice on tackling this book would be great as most of the videos about it are for much older books.

Thanks in advance!