unable to boot from SDCard

[Charles Tarkowski]

Thanks a lot, the solution was:
tried some other images, (monitor is still black) without eMMc, one works,
than reinstall eMMc, every time wants a passwort for root i not remember,
so start with jumper, remove it in 2 sec. and the result is:
start from SDCar and eMMc is visible,
so fdisk /dev/emmc..
delete all partions
and the system is so new like a baby
Hurra