Thank you for your reply.
Finally I got the motherboard boot up again! It was frustrated that no display at all. Then I tried to plug a display card and connected it to monitor, plug an USB drive with latest BIOS, unplug all other devices including keyboard, mouse & HDD, and remove the jumper for BIOS recovery. Then I powered on the computer and went to do other things.
After some time, I heard a beep sound and returned and found that there was display on screen showing the progress of updating my BIOS! After saw it all done, I put back the jumper and power on the computer and it worked again. However, I could not use the built-in display adaptor until changed some BIOS setting.
