I have tried with 7 different images, on 3 different SD cards. Copied with 'dd' or 'win32diskimager'. None has functioned.
Perhaps my BPI is defective, or they are my 3 cards. For information, the MD5sum cards do not match to the MD5sum image.
I tried to do a low level format on the cards, with no result.
My cards work correctly on other devices. And this cards work well with my BPI in the past (several image tested).
I no longer see what to do. Someone there an idea?