The reason behind the Video output changing
and Hence a black screen after upgrade

Before Upgrading (non 10.01)
After upgrading(10.01)
After downgrading(non 10.01)
YCbCr
S-Video
YCbCr
RGB
YCbCr
RGB
S-Video
Invalid
S-Video
Comp
RGB

 

As you can see the Video output changes between non 10.01 versions and 10.01 versions.

So if Output is already set to RGB before upgrading to 10.01
then it becomes YCbCr in the menu of 10.01 and you have to change back to RGB.

If output is set to S-Video before upgrading to 10.01
then firmware is unsure how to set output so screen can appear black.