Ultimaker 3 troubleshooting

[shukydesign]

Hello,
I’m troubleshooting an Ultimaker 3 board based on an Olimex A20-OLinuXino-Lime2 Rev.G.
I cannot find any NAND/eMMC flash populated on the board (NAND_F footprint is empty), and I also don’t see an obvious SPI NOR flash chip.
However, according to the Ultimaker recovery/install instructions, the printer can supposedly boot after the SD card is removed.
Does anyone know where the bootloader is actually stored on this board?
•   SPI NOR flash?
•   hidden eMMC/NAND?
•   boot from another board/interface board?
•   SATA only?
Thanks

[m k]

MCU usually has some memory.