MacBook Pro 'retina' Late 2015
To open the Mac you need a PL4 Pentalobe screwdriver.
The motherboard number is on the bottom left corner of the motherboard, hidden under the SSD.
The EFI-ROM (U6100) is a WSON-8 chip 8x6mm (64Mbit). Winbond W25Q64FV or Macronix MX25L6473.
The ROM in on the top (easy to reach) side of the motherboard.