Any WWII history buffs here? Can someone tell what was involved in applying to OCS during that time? [View all]

OCS is Officer Candidate School in the joint US Army/Air Force of the period. I have a reference that my ancestor applied twice, and was interviewed the second time, but was rejected both times. I'm wondering what the process was (there are no records, they were destroyed in the warehouse fire in the early 70s), and particularly what the interview may have been about - what questions might have been asked, if there was a standard screening, how long it would have lasted, if testing were involved, if they needed an invite to apply in the first place. This is kinda deep in the weeds, but surely someone knows a little about the process. Thanks.