Jetson TK1 doesn't display after Ubuntu upgrading....

Hi, all:

Recently, I upgraded the Ubuntu in Jetson TK1. And I can still boot up Jetson TK1, and remote accessed it via ssh. And the current Ubuntu in Jetson TK1 is

ubuntu@tegra-ubuntu:/etc/default$ uname -a
Linux tegra-ubuntu 3.10.24-gf455cd4 #1 SMP PREEMPT Wed Jun 18 11:20:52 PDT 2014 armv7l armv7l armv7l GNU/Linux

However, the HDMI output of the Jetson TK1 is just a black screen after a NVidia splash.

Well, let me summarize this more clearly:

  1. when I tried to boot Jetson TK1, the booting messages (in white text) went well, a lot of messages were shown "OK".
  2. After that, a NVidia splash came
  3. Finally, the screen turned to all black, and no Ubuntu login page at all

Can anybody help please???