MacBook Pro 'retina' 13-inch
To open the Mac you need a PL4 Pentalobe screwdriver.
The motherboard number is on the lower edge of the motherboard, on the underside of the board.
The ROM in on the bottom (hard to reach) side of the motherboard.
The ROM is a WSON chip (64Mbit).
To read or write the ROM use Medusa with A4052 (green) EasyFlash adapter (arrow points to the back of the Mac).