Why Bios missing！

Hi guys!

Few days ago, my lattepanda was broken, the red LED was on all the time but no display. After I re-flash the Bios follow the thread below, and then everything is ok.
https://www.lattepanda.com/forum/topic/312675

but I want to know why the Bios missing, I have do nothing special.

Have anyone met the same problem before, and in what circumstances ?

Thanks in advance.