The Launchpad Mini has a “feature” where if it is receiving power over the USB connection, but the computer is off, it will display a kaleidoscopic light pattern on the pads. I’ve seen this variously referred to as Fireworks mode, Vegas mode, or most ironically, Sleep mode.
According to Novation tech support, the solution to this is either to unplug the Mini, or edit your machine’s BIOS to stop it providing power to the USB devices when turned off, neither of which seemed very satisfactory to me, but in the absence of any other solution, I’ve been unplugging it after each shutdown.
Eventually I got jack of this, so I did a bit of digging around and found a partial solution.
With your Launchpad Mini in Fireworks mode (ie. after you’ve shutdown your machine), hold down the four round buttons on the right hand side in the top row (the buttons marked 5, 6, 7 and 8), and while holding them down, press the second button on the left in the top row (the button marked 2). The fireworks should go out.
This is a partial solution, because next time you shutdown your machine it’ll forget and go back to fireworks mode. Still, it’s a lot easier (and less wear on the cable) than unplugging it all the time.