Mini6410 doesn't boot any more

Hello,
last week i got my new Mini6410.
I tried to reflash my board via SD-card and something went totally wrong.
Now the board isn´t doing anything anymore:
The red LED is always on, but the green LEDs just glow and nothing more.
Reflashing via SD-Card is not doing anything.
I tried to connect to the DB9-com port but the interface is not supported
at my pc.
Any Suggestions?
Does somebody know how to access JTAG? Which hardware do i need.
Many thanks in advance!

Best regards,
Markus

Hello,
today i tried reflashing again and it worked.

Beste regards,
Markus