This might do the trick:

 

Reminded me of this

 

No, there's no homebrew which supports this.
Probably there could be one (HBL 2.5 disables the Home-Menu Button / Replace the Home Menu with a Screenshot-Button.

 

Get a grip, man...

Warning: Spoilers inside!

 

maybe some tape would do the trick.
you might need something rigid under the tape though to keep the button from depressing.

btw - nobody's going to code something like this for your special use case.

 

I don't know of any CIA format ones, but I used to have the same problem with my old 3DS and the best solution I came up with was folding tissue like a strip and taping it near the power button. This helped a lot when I had to EV train pokemon back then in Y.

I doubt someone can make the powerbutton mod because HB is more likely to fuck up every now and then, and since the battery is a pain to remove, and the power button being the only way to save it when it freezes.

 

Thought of saying HANS, Now that you mention it, I just realized how this is a big problem on HANS, turns out if you press the power button for even 1 second, it powers it down compeletely.

 

Make a guard, its easy and less invasive than messing your system files.
Just use some double sided tape and some rubber, or just some glue. Now I am posting that Sky3DS picture directly:

 

And i have the opposite problem
I need to push the power button real hard to get it done

 

Sometimes, especially in fast moving games, you can bump it accidentally. That happened to me last night when I was playing StarFox. I got to this one segment where you're fighting this skeleton thing with a tank, almost had it dead and then the "software closed" menu popped up.

I had my rage face on after that. My wife giggled at me. She thinks my rage face is cute.