Why does the gr die?

My b/f lives in Palm Springs California (right now we have 110 degrees outside during the day) and he planted the sod in March and now it has died in several places. He waters during the day 3 times (the landscaping company set it up this way), and I had suggested that the watering should be at night since I think that the water acts as a magnifying gl on it and it get burned. Am I correct or could it be something else. Underneath the sod it is sand only, so it has good drainage. Should we water at night or during the day? And why does that gr die? Any suggestions?