It would be hard to speculate on what happend. At 12,500 MPH it wouldn't take much to make a disaster.
If you wanted to focus on the tiles, there are about 28,000 of which about 5,000 are considered critical and the loss of one of those 5,000 are consided to make reentry impossible. If I remeber they are made of some kind of silica compound and glued to the skin of the shuttle.
Also in years past a guy in North Dakota or Minnesota claimed to have intercepted a reenntry conversation in which the crew was concerned about cabin temperature on reentry.