I have this modded saturn, I bought it in japan. The japanese seller sent to me instructions about the funcionality. My problem was, that before used it I lost this instructions and I don't know how it works. Maybe someone can give me a clue. I'm sure that the button is to use backups on the saturn, but I'm not sure how to use it. There is a small led near the button, and when you push de button, the disc stops inmediatly.
Ugh, what a hideous mod! The top part is particularly pointless! I'd imagine they've just put the access light back in, and you're supposed to do the swap trick. http://www.racketboy.com/retro/2004/12/learn-how-to-perform-sega-saturn-swap.html Not the best method to be using, really.
I find the modchip solution to be the best looking and best in functionality assuming you have a Saturn capable of being chipped and you can find a chip as well as being willing/able to pay what can sometimes feel like highway robbery for said chip. The swap trick on any console supposedly (supposedly because no-one has really done a scientific test on this but I don't see how playing anything but a disk would be good for it) wears down the motor and laser quicker than if you cold booted it with a disk in the drive. Given the laser would have to refocus and do some work each time you pull a disk out and pop another in it likely would wear out quicker. Then again CD-Rs will stress the laser out more than pressed media by virtue of needing more power to extract data from them. As for the top bit I applaud their wanting to add s-video and discrete stereo but it really should have been put on the back at minimum. Probably can buy a cable designed to be plugged into the Saturn without having to cut into the case at all and mess with the color scheme.
