What is the best way to flash BBB built into a product. This means that there is no access to the SD card slot and boot, power buttons. The user only has access to USB (host and hub) and Ethernet. What is the best way to flash a new image on this device?
That’s what the product developer has to figure out. It’s his product.
Best way, the way we do it. The SD slot. I suggest that you equip your product with a header such that an SD board could be attached for flashing.
You can force an Ethernet(emac) boot by setting the corresponding Sysboot pins then run the emmc flashing software from Nfs.
If you have any chance to make the boot pins to change to USB boot you can use https://github.com/ungureanuvladvictor/BBBlfs to flash the eMMC.
I come to the conclusion that there is no easy way to flash the BBB without access to either the boot button or the SD card slot (you can create a flash SD card image easily).
So we will try normal apt-get Debian updates for our first release. The next release release may include a boot button.
Did you try
The BeagleBone Black is flashed in production with microSD cards.