My Dell(app) not starting up.

I had this issue as well. Exactly how you describe it, except for me it's "My Alienware" app ilo "My Dell" app.

The solution that worked for me, to allow me to run the "My Alienware" app ( which came pre-installed in my Alienware laptop and also can be found in the Microsoft App Store ), was starting the "Services" app and modifying the startup type for "Fusion Service" to automatic, then clicking apply, and then start to begin this service. It had been preset to disabled. 

Doing this allowed me to be able to successfully run the "My Alienware" app which prompted me for an update ( worth it ). With the update finally completed, it now automatically brings me to the apps home page whenever I start the app.

While inside of the "Services" app, I had found a number of other services that were set to disabled which once enabled would allow me to run apps such as "Support Assist" and "Alienware Update".

Prior to getting this fixed I had been using Dell's Product Support page along with my service tag number to scan/diagnosis my laptop for drivers/repair issues.

Hope this helps !