问题
So I can flash the eMMC from the BBB. However I downloaded from wget https://rcn-ee.com/rootfs/2016-06-09/flasher/BBB-eMMC-flasher-ubuntu-16.04-console-armhf-2016-06-09-2gb.img.xz the Ubuntu image and extracted and placed it on the SD card through Win32DiskImager.
I put the SD card in the sd slot and tried to boot by pressing the S2 button while I connect the board to the usb for power to my laptop. I wait for LEDs to turn on and nothing happens. It works without the SD card, but not with it. Nothing blinks, nothing when I connect via ssh. Any ideas?
回答1:
So my answer was quite simple. It's best to get the UART Debug connector, see here. That way you know when you power on the BBB, the output of U-boot is displayed on your terminal when you serial connect (putty). If it does not find the image, the U-boot will send messages to the terminal notifying you that there is no kernel image.
Getting the UART Debug connector and connecting through serial is different than ssh'ing to the actual BBB. The output of the BBB (when you ssh) just notifies when everything loads up and the login information to the BBB is displayed on terminal. If your board cannot find the kernel, nothing will output, and you won't know what is wrong. However, if you connect serially through UART debug you wont have to worry, since you get to see output and error messages from U-boot telling you what's wrong.
*NOTE*: If you screw around the U-boot, which you should NEVER do (unless it really needs an update), that is the only way I can see there being no output whatsoever from the terminal when you turn on BBB and have the UART debug connected. If you didn't screw up the U-boot, then more than likely its a faulty BBB and you should return it.
HOPE THIS ANSWER WILL HELP OTHERS!
来源：https://stackoverflow.com/questions/38801785/beagleboard-black-doesnt-boot-from-microsd