Hi and Welcome to the Forum!
Have you any Security set up on the Initial Display?
An instant shutdown would typically be seen where the Initial Display has a Security Code assigned to it. The application is always started with the Default user logged in. If the Default user does not have this Security Code assigned to them then the Initial Display cannot load.
You then either remove the Security Code from the Initial Display or assign the Security Code to the Default user.
General practice would be to leave the Initial Display with no Security Code to allow the application to load with the Default user. You can then restrict access from the Initial Display to other Displays as required.
Regards,
George