Originally Posted by hostar
Lack of ability flash main (system) partition correct probably still persist.
That is not a problem with the fastboot program. Fastboot mode built into bist u-boot reports to the serial port that the image is too large and will be truncated (only a small part
of it flashed to mmc). That is why it completes MUCH too quickly. Unfortunately, it reports back to fastboot that it "successfully" flashed this partial (truncated) image.
So, fastboot MODE (not the fastboot program) has a maximum size limit that is smaller than the main system partition (mmcblk0p1), and it incorrectly reports "success" even though it fails for this reason.
Fortunately, we can write this partition image using a linux "dd" command, running it either from a RUNME.sh script, or from an SSH command shell (both methods documented elsewhere).