[Grammar] I have relived that game many times and I still don't know how I missed the goal.

[yi-ing]

Are these two sentences equal both logically and grammatically?

I have relived that game many times and I still don't know how I missed the goal.
I have relived that game many times. Still, I don't know how I missed the goal.

 

[yi-ing]

Only the first is natural.

Second one is ungrammatical or is just not natural.
http://www.oxfordlearnersdictionaries.com/definition/english/still_1?q=still
#2 definition: The weather was cold and wet. Still, we had a great time