Their is no "death certificate" such as the state issues for the war dead of WWII. The U.S. Army Quartermaster General's Office was responsible for compling, verifing deaths and dispostion of all military services as is my understanding. Their record is titled "Rosters of WWII Dead 1939-1945" that is online at Ancestry. The NARA as well as an LDS Family History Center should have it too.

Andrew D. Ballis was male, white, Catholic, buried according to kin in Illinois, Pvt. U.S. Army with service #.
This is probably the closest you will find to a death certificate. Now ther should be a burial certificate/permit in the county of IL he was buried in.

He enlisted in Chicago IL and has LaSalle, IL as nativity and that is county (LaSalle) where the family is living in 1930.