[Forte S+W]

Yep, that was the first video that I watched because the aftermarket safety I purchased was manufactured by NDZ Performance and a link to that video was included in the included instructions.
As a result, it was also the very first method I attempted to use, but to no avail.

If/when I ever try it again, I'll see about experimenting with some screwdrivers with thicker blades, but for the time being I'm burned out with it.
Frankly, I'm irritated most of all with Mossberg themselves for their nonsensical decision to use the sort of tamper-resistant, one-way screws you see in public restrooms to secure a safety switch of all things! What idiot lawyer convinced them that was a good idea?! If only it used an ordinary flat head screw or even a hex screw, then it could easily be replaced without the need for any special methods or struggle required.