All the Leds remain lit.

It is a BeagleBone Black which was successfully flashed. I tried to upgrade the kernel. However failed. I reboot the device and it stop working. 4 Leds remain lit. They are not blinking.

I tried to re-flash the board. However, when I hold the user boot button. The Leds are not up. Is my board broken. Any suggestion to make it work again?

Anh.

Have you tried to boot it fro ma system that is located on external microSD-card? E.g. a Ubuntu-version?