Hello again,
No problem, lets try to think again.
This is our solution to provide power for BananaPi M3
We used 5V, 3A dc power adapter.
BTW: i have to also check anper solution on our board.
I could only suppose that if your LED's are powered on but not blinking - BPI can't read information from sd card.
In our case we 1stly have to do sth with power cause after connect to OTG it can't work. No power, all leds were off.
Please also note that it is board v2 so i'm not sure where could be a difference.
Please try to use this command to write an image:
dd bs=4M if=system_image.img of=/dev/sdb && sync
or
dd bs=1M if=system_image.img of=/dev/sdb && sync
2nd command could take little longer time.
Let us know about the result.
Warm regards
Pawel