Hi, I had the same problem, described above. Did all the re-soldering but nothing worked...
I turned the the yellow potentiometer counterclockwise to about 10 o´clock... The "Hello, World" and time count appeared.
So my tip of the day is: Start with turing the yellow potentiometer and see if the problem lies there. If not go the re-soldering part. Less time consuming. Trust me, Hahaha