Does this place fix game consoles like for example, New Nintendo 3Ds XLs? Also, can they fix or "replace" the button parts and fix the game slot on them? If so, then what exactly is the price?

They do have a Geek Squad there but I don't believe they repair consoles. Best bet would be to go to the geek squad page on Best Buys website.

I am not sure you either might have ask Best Buy for more details and information call your Best Buy store call the Nintendo electronics company or go to an electronics repair store and ask about any technical difficulties associated with your Nintendo game consoles.