it's got oval buttons right? That should be your first clue.
hint on why I know it's a model 1
check the cable running from the mobo to CD-ROM unit. It drops in parallel to the face of the Sega Saturn onto the mobo, travels to the rear and underside of the CD unit.
I bet if you count the pins on it, it will be 20.
It also lacks the controller chip on the front face of the CD-ROM unit, it's actually located on the underside (that is why the ribbon cable runs to the rear underside)
model 2's can be noted by their 21 pin ribbon cable, round buttons, the controller chip is on the front face of the CD-ROM unit and is either 32 pins in square OR 64. The 32pin version has a much higher success rate of being modded.