Comment # 1 on bug 957668 from Ancor Gonzalez Sosa

Mmm. It's quite strange. The attached file includes only
/var/log/YaST2/y2start.log (which says that YaST was successfully started) but
no trace of /var/log/YaST2/y2log. YaST writes to that file very early in the
execution process, so it should be there.

In y2start.log there is only info about the attempt to run firstboot, not about
your second manual attempt. Did you run yast2 as root?