When a new update is released, the application is closed but in some cases, the new version is not downloaded and its not started again.
An error might have happened, and thus wyUpdate didn't install the update nor start your old version. See below:
Also, anyone know if its possible to, in case something fails, start whatever EXE I wanna execute so I can start my app again ??
Yes, see -startonerr="<filename>".