Everthing was fine until step 6.5, "Take the SD card image provided by MLE and burn it onto your SD card. " I don't know which image file this sentence is referring to, so I just burn the demo image file onto the SD card and copy the generated BOOT.bin and image.ub to the boot partition. The board was then successfully brought up.
The real problem happens at step 6.7. After excecuting aic/scripts/install_opencv.sh, some error message popped out. I attached them in errmsg.txt. It seems that the ethernet was disabled. I typed ifconfig in the terminal and only lo(the board itself) was detected.
This is how I configured my board. The ethernet cable is directedly connected to the router.
A very late answer, but I have the same issue.. It seems that the image is corrupt. As soon as I mount the partitions (from the image, before writing to the SD Card) in a Linux install and do an FSCK, then it finds an enormous number errors... after fixing them and copy the install to the SD Card and boot, there is no issue with eth0. It works out of the box.
But then there are 1000 other problems. The image is corrupt and there is no way to fix that. The only way is creating a build from scratch. I hope that the creators find a way to correct this and upload a working one.